> Can't you just install this type of app to your phone or pc?

The people who make that app, and host the servers that run it, they often like to get paid.

Not necessarily by you. Maybe they'll get paid by Google in exchange to allowing Google to show you ads in their app.

Maybe they sell the app, then, yeah, they're paid by you. Maybe some other thing. Like doing some statistics with everyone's data and selling the results.

Either way, they're working for you, but you're also working for them, in your own way.

Me, I work for myself. That's just how I roll. That's just how many of us roll. We enjoy the idea of being unaffected when the companies that own our services decides to hike its prices up, or punish users with an ad blocker. We like the idea that we'd be unaffected by a nuclear strike on the Silicon Valley, God forbid. We'll be sad and all, but our apps will still run.