Exist for a reason. Why do people hate haters? They hate the people you look up too. You want to be like the people they hate. You're not but if you were they would hate you too. But you're great and so it your idol. It can't be either of you. Your idol is beyond contempt. And you emulate their behavior so clearly you are (by extension) also beyond contempt. There must be something wrong with the hater. You're great and no one should hate you. Even if you're a little bed wetting molestee retard or a whore that fucks a retard instead of a real person. Obviously, no one should hate you. You deserve unearned respect.
Haters exist because you're a piece of shit and anyone who likes you isfoolish to do so.
The phrase simply means that you are doing extremely well and are very successful. Success, fame and fortune will inevitably come with a large amount of haters. This is not a bad thing, without haters there is no one to prove wrong. Understanding that hate is a sign of envy and jealously should be used to motivate you. Just remember, haters gonna hate, that just means you're doing well.
"Yoo dude did you see Dan Bilzerian's snap story!? Looks like he was hunting warthogs out of a chopper down in Texas with like five hot mami's, friggin epic!"
"No, I hate Dan Bilzerian. His company is gonna fail and he'll be a broke ass cat like me."
Dan Bilzerian has haters on the payroll and they are working for free.