Let me chime in here. I know many trained fighters, martial artists, guys who have won plenty IN THEIR DISCIPLINE. I have trained and competed in kickboxing, boxing, BJJ, and train MMA, and feel like im pretty decent IN THE GYM. But hell, there are definitely guys out there who have never trained a thing in their life who would fuck me up, as well as these other guys I mention that are very good boxers, grapplers etc.
Now I know Mike Tyson was an elite boxer, and not just some good amateur or pro, but I still have no doubt that theres plenty of people out there who could've taken him out.
I would even go as far as saying someone of his size who knew a bit of high school wrestling could've taken him down and pounded him out. And I say all this as a Tyson fan.