People have figured out how to hold stable value on blockchains by using them to issue contracts for difference. You can acquire a token that maintains the same value as the dollar, backed by people betting on price changes between the dollar and the blockchain's internal currency.
Volatility isn't a drawback of cryptocurrencies anymore, and it's going to be entertaining when countries with capital controls discover this.
Any time you hand something of value to someone with the expectation for future gain it's a risk. Suppose they setup two independent companies one makes major bet's ignoring price drops and another major risks ignoring price gains. By ignoring the risk they undercut the market. If the market is sable they make money. And their downside is limited to the value of those tiny companies plus the loss of one means gains in the other. Should one fail just start a new one rinse and repeat. In theory you could set things up so either no movement or any movement was a gain as people first handed you the money for what amounted to IOU's backed by junk bonds, stocks, tulips, or crypto currency's.
PS: Do this with 100's of millions$ and you either get rich or end in jail. Do this with 100's of billions and you often get bailed out.
All bets require a margin to be escrowed on the blockchain. If the bet goes bad, it gets margin called. The bets are also fungible—holders of blockchain "dollars" can trade them freely instead of relying on the original backer of the bet. There is effectively no counterparty risk.
Just to be clear there are only two types of actual US currency out there. The paper stuff and a leder of what 'banks' (or governments etc) control maintained by the FED. So, now you have a seperate DB not actual cash or physical currency. Which means you have counter party risk. Now if the US government can decide to insure 3rd party's which is almost as good as cash but as anyone that has delt with a banking error knows there is a world of difference between cash and IOU's.
That means e.g. Venezuelans would be able to instantly drop out of the Bolivar and get into a stable currency, therefore instantly bringing about the tail end of hyperinflation, which drops the value of the Bolivar to zero - because now not only does no one want it (as is the status quo in real life), but also no one has it, which is what Venezuela currently has control over (by not letting people freely get out of the Bolivar).
Volatility isn't a drawback of cryptocurrencies anymore, and it's going to be entertaining when countries with capital controls discover this.