At some point you will still have to trust the fiat system to meet your needs because that is the only way you can only enjoy the btc you have pending the time  that bitcoin will be accepted as a mainstream currency. What is there is just that one should only convert what is being needed at the moment to fiat while you keep the other as asset. Aside that, converting to fiat to keep the value can also work out if you don't keep in cash and cash equivalents rather in investing activities most fixed assets.