Against a street fighter, though? No. I'm very sorry, but no. Bruce Lee's sports would have very little effect other than probably be laughed at. (Which is a huge advantage in itself, though.)
Point is: In a real fight, techniques are bad. Because techniques are taught, not learnt. They're predictable.
Listen to Hauser, gals. They're completely right on that.
Me; I'd say: Martial arts are good. They teach about posture and demeanor, and those are key elements of avoiding a fight. Of not being attacked in the first place. If you are attacked: Fight up close and dirty. As soon as you incapacitate someone: Take a runner. Don't aim for the genitals; go for the throat and face. Don't scratch; use fists, feet and open-hand grabs. Twist, break, sprain, crush. Those are your only options. Because that's what your opponent will do.
And yes; size and strength do matter, as well as speed. Not the speed in landing a punch, but the speed with which you can rotate, twist, move your spine and shoulders, and..
Oh, well.. I'm not going to continue on this one. The easiest fights I had were against highly trained martial artists. Just.. Understand that, no matter how prepared you may think you are, no matter what kind of weapon you're holding, and no matter what your instincts say (fight or flight) your knees will be buckling with fear. Unless you are the aggressor, of course. That happened to me every time, and it was on a daily basis for years. I once brought a club. Wrenched out of my hand easily. I brought a knife. I'm thankful to this day they threw it away. I was held at gunpoint, but managed to outbluff him. (It's far harder to shoot someone who's standing right in front of you, looking you in the eyes.)
In other words: Don't get into trouble. If you see something happening: Walk away, and ring the cops. If people come at you, threatening: Cower until they really attack. Be submissive, and back away, until they really attack. Don't make the mistake of feeling invincible because of your training/weapon.