"This time is different" is always bullshit. In fact there's even a book called exactly that which covers 500 years of History of financial crashes and people saying that for some reason or other "things are different now" to justify "no more Crashes", is an incredibly common occurrence just before major Crashes.

Markets exist in a human society context, which exists in a real world context, were the only Laws that never break are the Laws Of Physics: no matter how much of a fantastical and magical imaginary fairyland the Financial Investment universe has become, there is always some link back to the real world (what would be the point for investors if their investment didn't somehow translate back into being able to get more concrete things in the real world), at the very minimum through the value of the currencies in which the investment assets are valued (if the Economy supporting a currency collapses, the real value - aka purchasing power - of investment assets which are priced in that current goes down, the number which is that asset in that currency can keep going up and yet it's actually worth less - you can see a good example of that by looking at the FTSE100 and the GDPEUR cross-currency pair when the result of the Leave Vote in Britain came out: the FTSE100, which is listed in British Pounds, went up right after it at the same time as the British Pound collapsed around 20%, so the real value of the FTSE100 and thus the stocks in that index actually went down even though the number itself was up)

(EDIT It doesn't matter how much of the transformation from "imaginary asset worth" to actual real concrete goods and services in the real world uses and abuses the subjectivity of "convincing people that this imaginary shit is worth as much as it is worth" to swindle people to give real stuff in exchange for la-la-land fantasy tokens - as shown every single time by Ponzi Schemes, such things always end up in running out of fools or the fools running out of money, and then collapsing, the only question being how far they spread before that happens)

This is why in my post I pointed out several links back from the stockmarkets to the broader Economy.

Beyond that, the broader Economy links to the broader society by in the extreme how humans react to being fucked up repeatedly (i.e. having difficulty accessing resources required for survival and seeing their quality of life plummet). I suspect that the current movements when it comes to ever more extreme surveillance, ever more shrill blaming of scapegoats (such as immigrants and transsexuals) by the billionaire-owned Press and Politicians and ever more extreme use of Force by the State against civil society movements trying to change things, is the current elites preparing for just that human reaction - a lot of very wealthy people are preparing (some even openly stating things around those lines) for turning Democratic countries into Autocratic ones rather than accept any changes to the machinery that makes them ever richer and lets them de facto be the top power.

I would say that the only uncertainty is not IF things will break, it's how far they will stretch before they break - judging by all that's happenning, there really doesn't seem to be any chance for enough of the people holding most of the money accepting that "this is unsustainable" and taking a loss for things to go back enough that a different route can be taken - as the Economy increasingly sputtered and growth stopped, they just doubled down on pillaging wealth from the rest of society and funding political movements scapegoating minorities and outsiders rather than addressing the reasons for the Economy having stopped growing.

As for specifically your point on algorithmic trading, that kind of trading applies to very short time frames - money goes in and then out sometimes in seconds - and its mainly a way of making money by front-running the information about trades done in different Stock Markets or things like news that will impact prices: it doesn't create market movements, it just tries to run ahead of them, so its not actually a sustained force to push the Markets in any direction.

I would say that the current overabundance of speculative bubbles (including the AI bubble and realestate bubble) are not the product of algorithmic trading but rather the product of the increasing concentration of wealth - especially following the 2008 Crash - which has moved a lot of money from those who have little and mainly Spend most of their money to those who have much and thus Save/Invest most of their money (something which also explains the current record level of Household Debt - the people at lower end of the wealth scale increasingly require more debt merelly to survive) so A TON of money was seeking any and all investment opportunities thus pumping out lots of asset prices purelly via more demand for those assets rather than due to the fundamentals of what backs them (for example, corporate profits) having got better. If you search for it, there are several people out there explaining it much better and in more depth than me.

Machine trading

Algorithmic or "machine" trading was very much already a thing and deeply ingrained into the market in 2008.

My savings are mainly in Gold. Actual physical gold, in a vault, in Switzerland, not some kind of paper gold certificate that's supposedly equivalent to the real thing but in fact is just a contract with a company with all the associated risks of it for a piece of paper that supposedly tracks the value of gold.

That position is a massive rejection of the entire Financial system, Gold being it's own currency and a really old one at that - essentially I'm positioned to counter the devaluation of the very fiat currencies in which investment assets are priced, mainly because I don't trust how they and the nations backing them are managed. (I'm in that position since 2012 and I would say that what's going on in the US is kinda proving that view I've had since then). Putting money in agricultural land would be a similar position, that that has geographical (and thus country and climate) risk plus I'm not quite ready to become a prepper.

So most of my savings are literally outside any main currency such that I'm basically shorting main currencies.

(You see, I worked in the Finance Industry for almost a decade and it's kinda like working in a sausage factory: once you see how they're made you stop wanting to eat them)

Mind you, I have a very long investment horizon - 14 years now and counting, with a return of so far around 500% vs the EUR - and whilst Gold is currently sliding down since its all time peak at the end of January, it's price now back to the level of the start of the year, that's fine when one is sitting on 14 years of gains and not really aiming to take money out until retirement, since in the current fucked up deregulated shit that passes for a Financial System nowadays there will be plenty of financial crisis in the meantime and Gold invariably goes up when shit hits the fan, the worse it is the more it goes up.

If your investment horizon is shorter, things are different.

Now, outside this specific ultra-low risk position I'm in, I'm not going to advise you on specific funds - all that stuff works as legal contracts in that to really know the risks you're taking you have to read the small print plus as we've seen from the changes to the Nasdaq 100 index rules, there's even more contracts under those contracts and they can even change those from under you to fuck you up.

Obviously I'm not gonna read the small print of that for you.

So here's a few more general things you probably should consider:

• Try and go for things that reduce the number of intermediaries between you and the value you're invested in. Every intermediary adds risk (not just of shenanigans but also of them just going bankrupt - a lesson I learned in 2008). Holding physical Gold is maybe a bit extreme but it certainly reduces the number of intermediaries (though I personally use a custodian, accepting the risk added by having that single intermediary).
• By all appearences the cycle of empire for the US is at an end and by all indications China will be next. If you're going with traditional and more liquid investment classes, you might want to be exposed to China stuff. I'm in Europe and, frankly, I suspect Europe will be dragged down by the US - maybe not fall as bad as the US but certainly it's not going to come out unscatted. Keep in mind that the time horizon for it to happen is unclear (maybe some years, maybe one or two decades) - I mean, it's happenning, but not very fast yet.
• Spread your eggs across several baskets: in other words, diversify your investments, even across investment classes, in case something goes wrong. Diversity is robustness. I still have a little actual cash at home (for things like interruption of access to electronic payment systems, like it happenned recently with a long blackout) and money in bank accounts in more than one country (and in different currencies if one counts Gold as a currency).

There's this phrase from the goldbug community (yeah, I know, but sometimes even some of those fanboys have a point) which goes roughly like this: when things get rough it's not the Return On Investment you should worry about, its the Return Of (The) Investment.

I recently moved a decent chunk of money to municipal bonds. Is it guaranteed to be safe? No. But it's a good way to wait out chaos. If cities can't pay their debts the market is in really bad shape, but not necessarily vice versa. And it avoids the "everyone sees the economy is about to crash" premium that you're currently paying for precious metals.