Never seen so much rubbish packed into one post. Must also paint devil's horns on the Xbox logo in your free time.

There's no disadvantage or downside in other people with a different platform being able to play a game you enjoy. If you're playing a thoroughly fantastic game on your xbox does it matter if someone else is able to play on PC or Xbox One consoles? Why would you really care other than for petty reasons? Xbox Series X owners can still play and enjoy the game. For Xbox owners that's a game that brings value to their purchase. The game or platform you play it on is no less valuable just because others are able to play it elsewhere.
I'm also skeptical how much of an authority you are on how "optimized" games will be for new xbox consoles. If they're running 4K at pc max settings at a flawless performance clip do you consider THAT as "optimized"? We are that point now with console performance. We are getting the highest quality settings from here on out on both PS5 and Xbox Series X, and that's a great thing.