Because for most of his life, he's Ben Solo.
You have no life
A meme-oir
PEEr pressure!
Your Sherlock Homie
Because they have a hard time puckering their lips the right way.
Kylo Ren: *takes off his mask to reveal his real face* Rey: Wow. Put the mask back on.
Because he made the First Order!
He's Ben Solo his whole life