TFA spoilers ahead if you somehow still haven't seen the movie:
The whole point of Kylo Ren is that he has an inferiority complex. He's a villain that's human and flawed. He wants to accomplish what his grandfather set out to do, only improve upon him; Rey sensed in him that he's worried he'll never be as good as Vader. He killed his own damn father because he thought it would free himself of any urges from the light side of the Force. Kylo is an unstable adult who wants to conquer the galaxy.
