X is used in maths to describe the unknown in equations. It entered pop-culture representing the unknown/mysterious or the different.
Musk uses it to symbolise difference or breaking from the past, which is ironic as he is becoming the modern embodiment of failed ideologies.
It's more effective with the X.
Also is the first meme I made, took 5 minutes. You can figure it out, be a creator, I believe in you.