We are here to replace the state's monopoly on money and therefore the state's monopoly on violence and therefore the state itself.

If you depend on the state to determine value, you cannot replace the state.

As for the problem of volatility and whatnot, you can use simple moving averages to avoid this problem. If a farmer wants fiat for his cows and you want to sell his cows for Monero, the simple moving average can be used so that the farmer gets the fiat he wants and the Monero price stays stable.