To play Devil's Advocate right back at you: it could be argued that one of the reasons cryptocurrencies are so volatile is that governments around the world seem to be lining up to try and suppress them or regulate them into irrelevance or oblivion, in one way or another.
How stable do you think the prices of fiat currencies or assets such as gold would be, if governments were constantly trying to ban them, regulate them out of existence, render their use nigh on impossible, or otherwise stigmatise their usage?
Governments around the world are terrified of 'the people' being able to conduct financial transactions without themselves [government] and the financial sector getting a cut. They also loathe the idea of the anonymity and pseudo-anonymity cryptocurrencies offer. Government wants to know, at all times, where you are, where you go, who you associate with, what you say or write, what you spend your money on... etc. etc.
To a large extent the populace has given them much of this on a plate already by voluntarily carrying mobile tracking devices wherever we go and by paying for most of what we buy with our debit and credit cards. Widespread adoption of cryptocurrencies would really put a spanner in the omni-surveillance works and must therefore be stamped out at all costs.