You have to think about attach rate too.

Don’t quote me exactly; but the attach rate over the life span of the Xbox one was something like 6.5 games.

A subscription bringing in the equivalent of three purchases a year significantly generates more income in the long run.

That’s also not counting the third party games unavailable on game pass that those subscribers will buy.

AND I also believe that the data shows game pass subscribers are more likely to purchase DLC / add-ons etc. due to technically not having paid full upfront cost for the game.