In the case the US dollar fails what can you use to protect yourself from that? Gold and silver are good options but not many have them and can be easily confiscated, but cryptocurrencies can be held without no one knowing you have them and even if someone knows they cannot take them away without your keys so in that way crypto is safer to store than gold or silver.
It's true that crypto is the better option, but the main problem is that there isn't one single crypto currency able to handle mass adoption. We have seen how Bitcoin's network crippled completely due to the bull run last year.
If Bitcoin can't even handle a few hundred thousand people using it in a single day, it won't ever be able to handle one million users trying to have their transactions confirmed within one day.
We have to look at our crypto currencies without hyping them up too much. As it is right now, they are all incompetent and haven't gone through any upwards scaling improvements to even remotely allow more usage.