I think people really underestimate the customer value of Steam. I have a library of 20 years of game purchases. From numerous different game companies. I can install all of them on any computer, now including my Linux machines, or a Steam Deck. If a device can't run one of those games, I can stream from another machine with Steam Link, including now to my VR headset. If a game uses Steam's multiplayer networking, multiplayer just ... works. No worrying about ports, NAT, anything. It just works every time, unlike every other multiplayer system I've used. If a game uses Steam Workshop, mods are available right in the same program, no extra tools required.
Besides the hardware and the game purchases themselves, all of that was free for me, the consumer. I get that Valve takes a big cut, but the value add of Steam is almost immeasurable from the consumer end. I've bought games from GOG but the experience isn't even close. Every game I've had to buy through Origin or Ubisoft directly had made me grit my teeth at their bloated launchers. Most of the physical games I've bought outside steam have been lost, damaged, or deteriorated with time.
If someone had told me 20 years ago, when I was signing up launch week and it kept crashing, that Steam would be this ubiquitous, useful, and free, I wouldn't have believed you. Steam is an incredible value add that makes PC gaming a tremendously better experience than console.