I'm probably being naive, but I feel surprised that in 2025, a platform like Steam (which has existed for well over 2 decades and has around 70M DAU) is having this type of issues. I don't want to downplay the complex engineering behind scale and massive surges of demand, but it's not like it's their first rodeo. What seems to be blocking users from getting the game is accepting payments, nothing computationally comp…
What I don't understand is why Steam and others don't use a torrent-like protocol on their back-end to reduce their bandwidth requirements large numbers of customers downloading the game at the same time. Back in the day WOW used used it for distributing large patches it seems to be a solved problem.
This makes sense because there are several live service games on steam that have hundreds of thousands of active players - any update will put a large instantaneous load on the CDN as all the clients are forced to update at the same time, and this happens extremely frequently so they've had to get good at handling it.
What doesn't happen very frequently is hundreds of thousands of people trying to buy a game at exactly the same time, because most games have pre-orders.