When I was a kid there was a discount store in a strip mall by my house that would sell these shareware floppys for like $2 a pop. So i'd pick up Doom, Wolfenstien, etc for cheap. I imagine many peple did the same.

Also keep in mind that the Doom Shareware floppy had like the entire first episode on it and eventually if you managed to get on a decent internet connection or knew someone who had the rest of the game you could copy that to your shareware version.

Also id games were notoriously easy to pirate. I mean hell Quake 3 Arena for example all you needed was to find pak0 and you were pretty much off to the races. Today it's one of the easiest games to "pirate" on linux. I have the damn pak files on a codeberg repo.