And do you actually think that the internet will go POOF just like that?? Some crypto doesn’t even need the internet to exists. Helium (mining) and their nodes is a great example. Use a search engine to fine some more information about that. Think of the helium network like ham radios vs other cryptos like digital audio transmission such as Spotify. If internet goes down, spotify goes down, though a network of radio nodes like Helium would still stay online.

EDIT: actually that first part isn’t entirely true either. Blockchains, while they exist on the internet, can exist on every single computer which uses that asset. For example, XMR (Monero) you have the option to download the whole blockchain locally or use a node where the blockchain lives. In my case, I use it locally. Crypto isn’t going anywhere. The only suckers will be those who keep their assets in exchanges or cloud based wallets