There is a huge difference between street fighting and fighting in a controlled environment.
But don't you think a professional fighter can do both and probably a lot better than those street fighters that are not training every day. After all, I really doubt someone just decides to become a professional fighter if they haven't done some real life fighting and has a propensity toward physical aggression.
I'm not talking about guns, knives, baseball bats, multiple attackers. That is a totally different situation. I know some say that that is the reality of street fighting and it's true, but if you want to evaluate just bare-knuckle no rules combat then that's what you should evaluate it as. Both sides can use knives, bats, and guns. If you want to talk about what style is better in a knife fight or stick fight that's an entirely different
issue.
I just believe a person is fooling themselves if they think that a professional fighter who trains every day doesn't have a natural advantage against one who only fights when there is a personal conflict. If it goes longer than two minutes the pro will win just on conditioning alone.