Why do all games made with Unity run like shit?

They don't, it's just that the only games you actually know are Unity are the ones that run like shit

its designed so literal retards can use it, but literal retards don't get that they have to optimize

General purpose engine, by virtue of being general purpose can't be fully optimized for specific game.

Yeah, forced "Made with Unity" logo was a stupid decision.

No it isn't, that's how they make their money
Everyone wants to get rid of the Unity badge of shame so people don't judge their game before it even finishes booting up