It means that now, when enough people think you're the shit, you have won and they haters/critics didn't. They were wrong for not believing in you.
Except you didn't win, because the critic never gave a shit in the first place. You're the one dumping all the emotional energy into the whole endeavor. You lose.
It means you get upset at people who don't believe in you, which means you're basing your own self-worth on what other people think of you.
It means you're living your life through the eyes of others.
It means that, all along, you've been doing it for the applause and not for the art. You lose again.
Applause is arbitrary and meaningless.
A real artist would have just kept making art, whether he got applause or silence or rotten tomatoes thrown at him.
Of course it's disheartening when people say you suck, but what's it to you? Why are you assigning value to that? You know who you are better than anyone else, therefore your judgement is superior.
You'd only get angry because you're afraid they're right.
Ali said "I'm the greatest. I said that even before I knew I was." Oh man. That statement is just drenched in so many layers of insecurity. I'm not really sure what he meant by it, of course, but that's what I get out it when looking at it from a superficial perspective.
If you have emotional autonomy, which should be priority #1 if you don't, a statement like that doesn't make sense. Because you would have known you were the shit all along. You wouldn't need other people to confirm it for you. Because you're all alone in this universe, and you're delighted for it. It means you make all the rules and you are the sovereign ruler of the universe. Which is fact, not egotistical delusions.
When you say "fuck the haters" it means that you don't understand the fundamental nature of how life works, and it means that all along you were chasing something that doesn't exist. You lose.