This would be a great read for people who make the comment "but it's not backed by anything". What gives many things value is it being back by gold, silver or something else.
However, in 10, 20 or even a 100 years from those things may be worthless to us. As a society we will find something else to place value in so I see no reason that crypto can find it's own place among mainstream values!
Precious metals may be worth less in the future, but they will always be worth something since they are tangible. A government's guarantee of value is worthless if that government ceases to exist, and cryptocurrency is worthless if nobody wants it/places value on it.
Crypto can struggle because it has no guarantee by a government, however, it's a global currency meaning you can exchange it with anyone around the world without the restrictions from governments like trade borders.