If you are a healthy well-adjusted person, possibly never:-). After all, X is a letter not a name, and just about the least-used one at that (except Q, which is also co-opted now by the similar group).
If I were to suddenly declare that my name was now the letter "A", how much arrogance would be required for that, to straight-up steal an entire letter of the alphabet for my own personal use? But then for it to be "X" instead... he knows he doesn't deserve his own letter, he seems just hoping for someone to push back against him, though nobody will.
So it is not just you - his chaotic evil actions affect everyone who uses anything that he touches.