Yes more the demand.. But you have to use the currency to buy stuff for it to be sustainable in the long run.. frankly people are expecting a huge rally somewhere in the future so that they can cash out. fiat.. i mean the whole idea of bitcoin was to get rid of banksters and their manipulated fiat.. kinda defeats the purpose of the whole thing when you convert coins back to fiat.. well its my personal opinion and most people tend to disagree with it..
well no, say price goes up to 10K a bitcoin.
All of a sudden I can spend many fractions of a bitcoin to buy lots of stuff, while being able to hold other bitcoins. I posit the higher it goes the more spending you will see, because BTC will have more buying power.