I haven't weighed in on this topic until now, but the wisdom I impart will be enough to convince you all.
I refer you to the greatest movie series of all time: "Rocky I-V." In Rocky I, Apollo and Rocky go the distance in an incredible bout. Both are completely drained after the match--but that is not why it is the toughest sport.
We move on to Rocky II, which begins with Apollo and Rocky in the hospital. Rocky's face is seriously messed up. He spends a couple of days in the hospital. Why? Because he got punched a lot. Getting punched in the face hurts. Apparently some of you have forgotten that.
Fastforward to Rocky IV, the best movie of the 1980s. Apollo fights Ivan Drago, the Mad Russian, and is **killed.** He did not die because of conditioning, but because he got the crap kicked out of him. Boxing killed him. Later, Rocky beats the crap out of Drago (after Drago had the cojones to say, "You vill lose"). Drago and Rocky once again end up in the hospital.
I agree that wrestling is a terribly taxing sport. In fact, I'd put it at #2 on my list. But we all sit here and debate the conditioning and weight cutting aspects--that's not the question. The question is, "What is the toughest sport?" If we answer that, it's obviously boxing. To my knowledge, it's very rare for a wrestler to die during a match, and it may not have happened at all. (Don't bring up the college wrestlers who died a few years ago--they died cutting too much weight the wrong way, not while wrestling.)
Boxing kills people (sometimes). Wrestling does not. Boxing too much gives you brain damage. Wrestling does not. Boxing = death, wrestling = life.
What's tougher?
Besides proving that boxing is tougher than wrestling, I have also proved a theory I have had for a long time: All problems in life can be solved by 'Rocky' references. Thank you. *bow*