Decentralized cryptos will be the alternative, not fiats rival or event replace it, both has various uses in their respective fields and will goes along each other. After all, who will want to guarantee all their assets in crypto if there is no guarantee that they will make a profit in the future.
As far as I know, crypto is a very volatile business and there is no guarantee of profit in it.
So far there have been no fatal losses for people who really understand crypto unless they are people in a hurry to sell their assets and people who choose the wrong coin to invest. choose the right cryptocurrency and choose a good coin like bitcoin, ethereum and others, then you never experience a loss.