That’s an opinion, not a fact. Here’s another opinion.

Constantine adopted Christianity because the people adopted Christianity and if he didn’t follow suit, bad shit would’ve happened, mostly to him.
And the capital was moved to Constantinople to account for the growing asian influence that was beginning to threaten the empire. The west fucking up after that would have happened regardless of the capital being there.

The Abbasids fucked up the same way and no one gives them shit about it.