Theory
This is about Young Justice, the DC animated tv show. Spoilers ahead.

GUYS I JUST HAD AN EPIPHANY! I KNOW WHY SUPERMAN HATES SUPERBOY SO MUCH!

In season one episode one, the team, which then consisted of Robin, Kid Flash, and Aqualad, break into a Cadmus facility and find Superboy, a clone of Superman created as a failsafe in case of another attack from the Man of Steel. Superboy was created as a weapon to be used in case of Superman turnings rogue again. The reason Superman hate Superboy so much is because every time he looks at him, he is reminded of the fact that there needs to be a weapon to be used against him in case he goes rogue again. He is reminded of the time when he turned against humanity, and he's reminded of the fact that they're people out there who are terrified of him, so terrified that they are willing to go against the law and illegally clone him, just so they have some closure, that they have some protection in case he goes rogue again. And for someone who's strives to be a beacon of hope, that can hit someone pretty hard.

OR MAYBE HE'S JUST AN ASSHAT WHAT DO I KNOW HAHAHHAHAHAHAHA

So, what do you think? Do you agree or disagree? I love to hear feedback. Don't forget to ask me anything!