For cryptocurrencies with fees priced with gas, price volatility is not a problem. As the price grows, number of gas units per operation will likely go down, but will maintain its "stable currency" price.
Ether's price doesn't have to stay fixed. It can grow or fall, increasing or decreasing economic security of the network (assuming Proof of Stake). There is no good way to ensure price stability, and there's no reason to. We don't complain that stock prices change.
That's why smart contract cryptocurrencies have stablecoins: to address "stable use case". But this is just one of many possible "dapps", many don't need external peg to function (NFTs can be priced in the volatile ETH just fine).
Ether's price doesn't have to stay fixed. It can grow or fall, increasing or decreasing economic security of the network (assuming Proof of Stake). There is no good way to ensure price stability, and there's no reason to. We don't complain that stock prices change.
That's why smart contract cryptocurrencies have stablecoins: to address "stable use case". But this is just one of many possible "dapps", many don't need external peg to function (NFTs can be priced in the volatile ETH just fine).