I'd assume that's part of the reason for the online multiplayer focus of MS' 1st party. People are more likely to stick around beyond that month if they can't "finish" a game but instead can just keep playing it online.
If they can make it right the revenue from Game Pass and XBL for the multiplayers will be higher than if all the subscribers had bought the game only. And as you said, good MP have people coming for months. Also it's 100% MS participation.
duduspace11 "Well, since we are estimating costs, Pokemon Red/Blue did cost Nintendo about $50m to make back in 1996"
Mr Puggsly: "Hehe, I said good profit. You said big profit. Frankly, not losing money is what I meant by good. Don't get hung up on semantics"
Azzanation: "PS5 wouldn't sold out at launch without scalpers."