If there is no guarantee that the bitcoin's price is gonna go up and allow the average Joe to profit from it, why should he buy bitcoin to use it as a currency?
Average Joe should use it for all of his online purchases through Amazon, Best Buy, Target, any retailer who sells gift cards through gyft.com. Why?
Because Joe gets 3% discount for using bitcoin, that's why. And Joe can insulate himself completely from bitcoin price fluctuations by converting USD->BTC at the time of purchase at a place like coinbase.
-because no fees? Volatility can fuck that over real good, so no point in saving 1-3% when you can lose 10-30% in a few days. You might argue that over time (IF bitcoin succeeds) volatility will gradually decrease. While I have doubts about that, in the long run bitcoin transaction fees will be higher anyway. I guess you know that miners “need to be paid” in order for bitcoin and the blockchain to exist, whether thanks to ridiculous inflation, or transaction fees. The blockchain is not gratis.
Peter Todd said it himself: “regarding fee economics, we’re fucked”.
For similar network security, we are either getting ridiculous monetary inflation or higher transaction fees.
On top of that I seriously doubt the average joe cares about going through the pain in the ass to get involved with bitcoin only to save 1-3% (right now that high bitcoin monetary inflation allows it) for the stuff he has to buy online.
If you convert BTC to USD to avoid volatility you pay fees for that too (less, but still). And if you buy bitcoin just to convert it to USD right after to avoid volatility and if you buy BTC only when you intend to spend it online that doesn't add any demand pushing the price up, since the merchants just dump the BTC anyway.
In other words, the whole system as a currency is a mess, especially long term.