Thank you all for the insight. I have been buying games from Steam since I was 10 years old, and when a game isn't on Steam I usually don't bother buying it. It's just too convenient to have all your saves, mods, friends and games in one app, transportable easily from computer to computer. Support has always satisfied me, it used to be dirt cheap here in Turkey and I like the UX aspect of it too. Plus I'm too much of a normie/zoomer to know what a DRM is.
It stands for Digital Rights Management. Essentially it's a form of copy protection to keep you from pirating games (and sometimes other things companies don't like, like modding or changing it yourself). This can take a lot of forms and for instance back in the 80s was often "you need to access a specific page in the manual to answer a question in the game or it stops working", but in this case I'm talking about DRM software.
Back in the day you generally bought a game and for all intents and purposes owned it. The source code was encrypted but otherwise you owned and nobody could take that away. DRM changes that, and generally prevents things that are unequivocally legal and fair use, such as making backup copies for yourself. Some are more intrusive than others, and it was VERY unpopular with a lot of people back in the day. Notably, in many places it is illegal to circumvent it or even discuss circumventing it; both the US (the infamous DMCA) and EU have laws enforcing this. Some DRM operated in ways, often rootkits, that would unintentionally create security issues for computers that had them installed or were functionally all but impossible to uninstall even if the software they came with was no longer on the computer. Sony, for instance, got in deep shit for force-installing DRM on CDs in 2005 that caused a security vulnerability on computers and had to create a tool to remove it as well as exchange all the CDs for ones without the DRM. Amazon has remotely and without warning deleted books people had purchased off Kindles because DRM lets them do shit like that (hilariously, this included
1984 at one point).
Steam is DRM. That is one of its primary purposes. As an example to illustrate this, my wife and I both own games on Steam, and while we have two accounts, there are games we both play that is on the primary account. It is impossible for us to play two different games at the same time on that account unless one of us completely disconnects the computer Steam is using from the internet (you could also put it in offline mode but Steam can randomly turn itself back on sometimes without asking when you do that). If you accidentally let both of them access the internet at the same time it will instantly kick the first person out of their game without so much as a warning. Supposedly the new Steam Family solves that issue, but that went into beta last year, which is an awfully long time to not play two different games we legitimately paid for in the same house, something you didn't ever have to worry about prior to Steam. Steam also does a variety of things I find very annoying like the aforementioned turning itself on/putting itself online when I did not ask it to and in fact told it not to, updating games even when it's been set not to do so, or refusing to play any game that hasn't been updated unless you again disconnect it from the internet so it can't find out there is an update (I live in rural Australia and have at times in the last decade and a bit had to make do with extremely limited internet to the tune of about 1gb a month, and you imagine how much I loved Steam turning itself on and helpfully trying to autoupdate things when it was set not to). Various features of games won't work right if you're not in their cloud mode (that's more bandwidth used, as well as taking away control of your own files), notably including the Workshop, and so on and so forth. Paradox games will in most cases actually work without launching Steam first (most games won't), but nowadays it'll usually eff up the DLC and of course there's no non-Steam multiplayer.
And if the Steam servers ever die, or if Steam removes a game and chooses not to let you continue to download it, you're not getting it back again (and the stuff Steam provides will never work again, like multiplayer, unless you can mod the game to jury-rig a new multiplayer system). That game isn't yours. You're dependent on them to keep providing it for you. All those nice features people like about Steam? They're the spoonful of sugar that finally got people to swallow DRM and like it when it was almost universally hated in the naughts like, hmm, EA is now.
GOG has none of that. You buy a game from GOG, you download it once, it's yours. You don't need to connect to the internet every time you use it, you're not forced to download anything to play it, and you can back it up on a separate hard drive and that copy will work if your first hard drive dies for whatever reasons. It's DRM-free. It belongs to you, in the same sense that video games always did in the past. That's pretty much one of it's main selling points. They've even offered free DRM-free downloads of some games (like Masters of Orion) where if you bought the actual boxed copy of the game you could no longer use it because the DRM systems of those games was defunct and would no longer validate.
itch.io runs on a similar philosophy and a lot of indie games are published through there, so that's another place I buy from when I can.