The difference is that enough people accept the current system without understanding it that you can use it for your needs. Not enough people use bitcoins that you can gloss over details.
If the Bitcoin monetary system breaks, only those using Bitcoin for savings or investment get hurt. Those who use BTC as a means of payment (buyers and sellers) have little reason to care, so long as they frequently convert excess BTC into other currencies.
That's not so different from the U.S. dollar. You can buy and sell stuff using U.S. dollars, but unless you foresee the value of USD going up (a kind of deflation), you don't want a pile of USD under your mattress. (Also, it's uncomfortable.) Depending on your economic outlook, you want the money in something else: metals, some sort of investment vehicle, or a basket of [foreign] currencies.
