>>88702875He spent pretty much his whole life getting shit on and no one ever believed him, to disastrous result.
He's was reasonably sure that his father and king are both dead and his planet conquered by traitors and alien invaders.
Meanwhile, he's stuck on another planet, powerless to do anything about it beside surviving weekly assassination attempts from across the galaxy while protecting the princess from the same.
On top of that, he had to go to high school, which in addition to being a nightmare on it's own, he viewed as a complete waste of time and a safety risk for both himself and the princess.
Quite frankly, he had every right to be as upset as he was.