It's not going to 'magically' drop to zero. It is going to drop to zero.
If it hits $1, I will just stock up. Traders getting out is good for me.
I am in Bitcoin, or any really viable replacement that emerges, long term for reasons fickle speculators do not care about. I fundamentally believe a healthy society needs a reasonably private, international, censorship resistant, and open source financial system that works over the internet. I see such a thing as having more -real- value than the US dollar that a small number of people can print more of at any time for political reasons.
99% of crypto users sell, or abandon their wallets
Remaining users are HODL, and even have some cash left
Demand falls, prices falls, mining difficulty adjusts, HODLs keep buying
As difficulty falls, there is a real risk of something-something-51% attack
So HODLs (acting rationally) need to spend more $$ to boost prices just to protect their existing coins
So now, we have a finite asset (coins), which do not generate income, but require non trivial constant $ cost just to protect it?
Say everyone gets out except you. You own all the bitcoins in the world. Now what?