I think Main problem of crypto is adoption but eventually no matter how hard we do think off we cant really go to a point that we can able to go on full scale.
We should find out the reasons why adaption is the main hurdle in crypto currecny. If you analysis you will find the bitcoin price is changing every day. You bought bitcoin at 4000$ and next day it can be 3800$ or 42000$, we never know. This much movement in the price is certainly not good for the adaption as people like to use money which is stable in value.