When government policy removes the necessary attributes of money from its currency, people will seek out a medium that has those necessary attributes. If it wasn’t bitcoin it would be something else. Bitcoin may or may not be the be all and end all of a currency but it is clear that all of the world’s currencies are in the process of being destroyed. People will take a chance on something else rather than hold a countries legal currency, as chances increase that holding the official currency will impoverish them. That is where the demand is coming from.
Besides, it is increasing in value. In todays economic climate, rising prices don’t even need a reason for going higher. Stocks go up for no reason at all, so why not bitcoin? Bitcoin is not only new currency we will see. Smart people are not going to go down the drain with their country’s currency if there is a way to avoid it.