If you have the time for it and it honestly is fun for you, then go for it.
Otherwise, I recommend pepper-spray just like I wrote above.
Cheap, no time required and is more effective than fighting someone.
Most men don't know how to fight either and size doesn't determine who will win a fight if there are no rules and all techniques are allowed.
Size makes people do not even try you, so you win the fight without even fighting, which is mastery of war according to Sun Tzu. Also you do not need to hit as much as someone with no strength. You can also just lift them up and throw them on the ground crushing their bones.
I agree with the no rules and techniques because you will be unable to do shit if the other person just pepper sprays you.
Fighting sport cannot compare to a street fight, which is another reason why it is a waste of time.
Get boxing gloves and smash the shit out of each other, that will be better street fight preparation than any "fighting sport".
On the street you destroy your opponent with full force, hold back, start talking, or try thinking and you lose, at which point your opponent can do with you whatever he/she wants.