What do you do when you have a burning desire to fight, because you know you're the best?

You tell off a few gang members and sway them into your view.

Since a fighter fights only one opponent at a time, the only thing he or she can be sure of is that they are better than the opponents they have beaten so far.

Anyone that thinks that they are the best has already made their first big mistake before they even get into a fight.

...

You fight. You fight to survive, then you fight to win, then you fight the urge to fight, then you fight the good fight, then you fight authority but authority always wins, then you fight city hall, then you fight the system, then you join fight club. But, don't ever talk about it.

hang on to that hallucination a little longer. somebody is likely to kick your teeth down your throat in the near future.

you (or whoever you mean) enters some local martial arts tournaments and see if you're right (although I'd recommend non/semi contact first)

start amateur MMA or get into the full contact martial arts bout fighting circuit.

You take your medicine for that mental condition, and hope the delusional behavior subsides.

become a pro fighter

get in bar fights

beat your wife

who can say?

I'd remind myself that I'm not and that there's always someone better.