Whilst I’ll agree with your statement some people prefer a service to use rather than self hosted.

Great! They can prefer that. Lots of people (most people probably) even need services, because they lack the skills and / or equipment.

That doesn't change the simple truth of "the only infrastructure we can trust is our own." My goal with that statement is to educate people as much as possible NOT to trust the third party services they're using, even if those services supposedly care about privacy and security.

I've also seen a huge outpouring in recent weeks of people who are suddenly very eager to learn about and use self hosted infrastructure (or get access to someone else's self hosted infrastructure). For some reason, I wonder what that could be. I've never seen anything like it in my life. I for one intend to encourage the shit out of it.

I recently discovered Filen and all their clients are open-source. It claims to encrypt all files before uploading and I did notice my CPU usage ramp up quite a lot during it. Though, I currently lack the time and expertise to audit their code.