As others have said, there's a massive difference between boxing and regular street fighting. It's like that Michael Caine line in Get Carter - something like, 'you're a big bloke, but you're out of shape, I'm a professional, now behave yourself'. It's along those lines, anyway. Until ten years ago I was in law enforcement, had to have weekly self defence classes, monthly medical, we were out on surveillance and arresting people pretty regularly. We had quite a few hairy moments - guy in a warehouse outside Blackburn came at me once with a metal pole, properly meant to take my head off, that was one that sticks out - but it was always against guys whose main job wasn't the fighting, we were just catching them at something else then sometimes they'd make a debate of it. I'm a big enough guy in decent shape with that experience over several years and I was good at the job, but I would not see out the first round if I got in with a boxer. It's not just the speed and the fact that we civilians aren't used to being hit that hard, it's also controlling the space, understanding what's around you. If a nutter rushes at you in real life, you leap out of the way, in whatever direction instinct sends you. Try that in a ring and you'll either bounce off the ropes and embarrass yourself in a crumpled heap or be clattered by the timed followup. Everyone I ever fought was both desperate and an amateur, and I had to train to make sure I came out on the right side of those encounters. Against a not-desperate, experienced, fighting-focussed professional? No thanks!