Everything that you can buy is an asset that you can sell. That is not enough to make it an attractive investment.The point being that crypto is an asset that you sell.
I think the point about crypto is that it's intended to serve as a currency - there's a clue in the name "cryptocurrency" (meaning "hidden currency"). But in fact it's not much used as a currency, and it has characterestics which mean that it doesn't serve especially well as a currency.
(Which is not to say that it might not have characteristics that do make it an attractive investment. But you wouldn't be wise to invest in it unless you have identified those characteristics and satisfied yourself that, yes, they do make it an attractive investment. But, considered purely in terms of doing what it was ostensibly designed to do, crypto doesn't look crash-hot.)