This might be a bit too extreme. But any other reasonable sporting challenges outside the popular marathon/ironman/70.3 which average athletes with family life can approach?
I would rather run-job 50 miles and get sleep. That seems stupid.
The line I draw in endurance is sleep deprivation. I'll stretch it to a 20 hour thing, but that's it. IMO if you are doing endurance activity (already questionable health-wise for anything over a couple hours IMO) with little to no sleep, then it doesn't seem like an actual positive thing in your life.