I feel like it's weird that they keep establishing the fact that you can obtain enormous power if you're willing to sacrifice.
If that's the case, wouldn't every Nen user do that in a situation where there's about to die?
"This guy is gonna kill me for sure, I'm gonna give up my Nen abilities forever to get crazy powerful for this fight." And then you win. Sure, you pretty much have to retire afterwards, but at least you're alive.
If that were the case, wouldn't he also have, like, 2 foot long fingernails?