SIE's total revenue (not profit) was $27bn, so you're talking about 4% of their total revenue. And then they would lose an absolute ton of revenue on top of that, due to all the lost sales from people playing the games on PS Plus instead. How many sales of Starfield do you think Microsoft lost out on because it was on Gamepass?
There's a reason why people say Gamepass is such a good deal- because it's ridiculously unsustainable. You're getting $70 games at launch for a fraction of the price. Microsoft are bleeding money on it.
I am not using Gamepass at all because I am more an old games playing for hundreds hour guy. But:
How many people are cancelling Gamepass when they finished the game for 70 bucks value? The next 70 bucks game is just around the corner, not even talking about to be too lazy to cancel the sub people.