Of course, that is what everyone who starts a fight says... ;-)

I don't have the expertise to judge if Jared Leto should have died from that beating. I will say I've seen some guys who have taken horrible beatings in a boxing ring and not died.

Mostly I'm commenting to clear the record: You can definitely be killed by a single punch to the head, but NOT by having your nose bone shoved into your brain. To my knowledge what usually causes the most damage is a sudden twisting of the neck where your head moves really fast and your brain inside gets slammed into the side of your skull.

Punches to the back of your skull (rabbit punches) can also do massive damage (including death) which is why they are illegal in boxing. None of those in Fight Club.