[dotnet00]

Technically, with crypto there's always the less than legal or privacy oriented stuff. Unless you're expecting all that to suddenly disappear there's still utility to back its value there, even if not to maintain its value at the rather overinflated values cryptocurrencies like Bitcoin have (which are less practical for such purposes compared to say, Monero).

Plus, for the value to completely zero out you'd need lots of large organizations who have lots of money (be it ones who've borrowed it or ones who are 'holding' it for others) to not only run out of said money but also be unable to pull in new people with get-rich-quick schemes. Miners and stakers would also need to completely lose trust in cryptocurrency.

So, to zero it out, you would need a global economic crisis so large that it educates pretty much every 'sucker' out there, which is pretty unlikely to happen right now.