Steam?
There's really two different Steams, there's the beloved one with 30 - 50 year olds getting great value from good games and frequent discounts and bundles. Then there's the shitty stuff that the kids plow money into where they pioneered concepts like lootboxes, some of their biggest cash-cows may become illegal under the EU's Digital Fairness Act.
They seem decent enough. I barely play games these days, so I don't fully understand the value they add. Just seems like a convenient app store that lets me port my collection across different computers.
That convenience is everything. Doing it well, and not falling into the trap of putting profit (too far) above users is the challenge that is too hard for other players (except maybe GoG) to get right. It's like WiFi. You go somewhere, connect, it works, and then you don't think about it unless it's surprisingly fast, or there are problems with it. Everyone else's offerings on this space just feel janky and liable to take your money for some reason. Steam, for the majority of its users "just works". That's not to say there are zero buys with the software and that nobody has valid complaints about it, but just that in general it's great.
It's still facing the headwind that a lot of people still don't believe that Steam can give you a lean-back experience which is fun like a game console. Some people still think PC games all have sweaty keyboard and mouse control schemes and those crappy huge joysticks from the 1990s that were always falling apart and had to be recalibrated every few minutes -- and that's what is keeping the PS5 alive.