I don’t think it can be called cash since no one is going to accept it.
Like it’s so stupid, even if the other person were to accept bitcoin or whatever they’ll still need to verify if the address contains crypto or not and whether the private key is valid (both of which needs internet access on some electronic device).
but $100 would be clearly marked as such here I just have the word of a crypto-bro
love to hold a 100$ bill, oh wait nvm sorry it’s actually 87$ as of today, but don’t worry, in a month it may be worth 50$! or 40, no one had thought about this before