liberals tend to want to shift capitalism towards something more equitable

No, they don't - they try to reform capitalism to head off revolt against the capitalist status quo. That is why liberal reforms to capitalism (at best) only makes life better for a certain part of the working class - see how Roosevelt's GI Bill left black vets and their communities out in the cold for an example. When this fails to protect the capitalist order, liberal-types will happily co-operate with fascists to violently repress the working class - see Weimar Germany for an example of that.

If you are the reading type, I'd suggest Clara Mattei's The Capital Order: How Economists Invented Austerity and Paved the Way to Fascism - I haven't encountered anyone who explains the history as well as she does.

Liberals are not your friends - Malcolm X was perfectly accurate when he described them as "smiling foxes."

I appreciate you trying to answer a question in good faith, but you're conflating 'liberal' with 'vaguely left-leaning', and none of what you've said makes any sense outside of current US political 'discourse' where 'Liberal' means 'slightly left-wing'. 

What you describe as liberal economics is closer to Keynsianism or Social Democracy. 

In economics, the 'Liberal' school of thought is generally against regulation and interference in the market, seeing it as being 'self-regulating'. In economic terms, Reagan and Thatcher were Liberals - hence them being associated with 'Neoliberalism'. 

The whole thing you said about Capitalism tending towards monopoly is actually a very Marxist/Socialist idea - Liberal economic theory tends to argue that monopolies form because of government and that they wouldn't occur in a truly free market (although its more nuanced than that, there's major disagreements over 'Natural Monopolies' etc. within the Liberal school). Source: look up any Liberal economist/thinker and their view on monopolies. E.g Friedman, J.S Mill.

Capitalism being an economic system doesn't make it apolitical. 'In theory' Liberalism and Capitalism are very very closely intertwined, it's not implicit, it's absolutely explicit if you read any Liberal political or economic theory. 

Economics is inherently political.

https://plato.stanford.edu/entries/neoliberalism/#Libe Sections 3 and 4 of this are a decent starting point.

Also the idea of slightly changing our voting systems as the way to drive change is quite hilarious. Sure, moving away from FPTP would probably help a bit, but it's not like countries with other systems are doing fine. These issues are more fundamental. And historically, fundamental change has never occured through small technical adjustments to political systems.

I believe that’s how it works, but I just don’t understand how that makes any sense. They’re just playing with numbers in the air, making a line diagraph go up and down… I just don’t get it.

Ok, so what percentage of income do the various income brackets pay?

https://en.wikipedia.org/wiki/Economic_liberalism

Well you need to start with a bunch of billions and some billionaire friends.