Sure, his parents didn't pay enough attention to him and his inferiority complex is understandable since the princess is a crazy genius who helped the kingdom with many of her inventions, but he went about it all wrong! First, he tried to destroy Euphie's reputation (who he also envied because she's better with both the sword and magic than him) and annul an engagement that could've very well led to Civil War, and later on he tries and almost succeeds in killing the heroine to get her power that'll let him hypnotize the country to following him, then he tries to kill his sister...and I mean really tries. And to top it off, after he's defeated, he's just exiled?! That's BS, he was a would-be murderer who put his temper tantrums above the needs of everyone around him. He's the friggin' Kylo Ren of this series! Daddy issues don't absolve him of the crimes he would've committed if he was stronger or his sister was weaker.