What you are referring to is asset encryption, not DRM. Many games have DRM (e.g. Steam API and Denuvo linked into the executable) but do not encrypt their assets; it's mostly "live service" games and competitive games with matchmaking and anti-cheat that do, usually with the intent of preventing future update leaks. On the other hand it's also common for DRM-free games to use custom (usually unencrypted but possibly compressed) asset and archive formats you can't easily open, especially if they are made using an off-the-shelf engine such as Unity or Unreal.
For what it's worth, there are open source projects that will pretend to be Steam that will run many downloaded Steam games quite effectively. All you need to do is drop a few DLLs and text files in the game's folder and you're good to go. For a safe version you need to figure out how to compile the source code yourself of course but on this forum I don't expect that to be much of a barrier.
Games with DRM crapware like Denuvo and many multiplayer games are more difficult to pirate, but the basic Steam DRM is pretty useless. That's good, in a way, because when Valve inevitably goes bust these games will still be playable.
However, if you can afford to spend 15 bucks on a game, I don't see why you'd go through the effort of downloading (and virus scanning!) games. For kids and poor people I can understand spending the extra time and effort, but for people with jobs that value their free time I don't see the advantage of just paying for the game.
I suppose the lack of demos is a reason, you don't want to spend 15 bucks on a game that turns out to be boring or broken. I pirated CP2077 to check if it could run on my PC but after a few hours I paid full launch price for it, they could've convinced me with just a demo despite the negative media attention. I still remember the Just Cause 2 demo where the demo alone was a great game you could play for many hours and the full game was even better.
