I'm thinking instead of paying like $100 for Windows 10 to use Ubuntu or something like that. Then I would like to know if you can play games on it (I'm thinking of minecraft).
If you stick with big-name Linux distributions (like Ubuntu) and big-name games (like Minecraft), you should be fine. The intersection of those two user bases is substantial and should leave you with plenty of support options. (Just Google "Ubuntu 18.04 Minecraft," and you'll find plenty of recent walkthroughs.)
If you want to try something more obscure, you might be on your own, or at the very least, good documentation might be scarce.
There's something no one else has mentioned yet: gaming on Linux is not limited to Java games (like Minecraft) and Steam. There's a fair number of games in most distros' repositories, and if you can't find it there (or the game is not up to date), you may be able to find it online.
One of my favorite games is Xonotic. You can download it for Linux, Windows, and macOS (not *BSD unfortunately). It's definitely worth checking out if you ever play arena shooters.
It depends. Steam game compatibility with Linux is ever expanding, but games outside of steam would need native support (like Minecraft Java), or would have to be run through WINE
yes, compatibility is ever expanding because of Proton
Minecraft works on Java, so it is a no-brainer to install (the original, getting the next one that is designed for windows might be an issue).
Steam works directly with Ubuntu, so that is a good place to start. Just don't expect an extensive Steam library to all be there (but you might see more than you expect).
There are claims that fps is as good as windows (presumably things with a full Linux port), but that hasn't been my experience (even with Kerbal Space Program which comes with the official Linux port). Depending on your hardware (especially the GPU), you might get more "bang for your buck" with that $100 MS price than paying a similar amount to Nvidia. One great thing about Linux is that you can try your entire build with it before having to cough up for Windows, so I'd certainly recommend trying it first and seeing if you still feel that the ~$100 is warranted.