A bubble is a bubble, people buy in to it on the hope of it will be worth more in the future. I don't see a great deal of re-use in the technology behind btc either, yes its decentralised but it takes a lot of energy to maintain the block chain. Is this really the best way to have a global currency?
Bubbles are fun if you know how to use them. It attracts people.
It needs to have an element of intrigue and a promise of opportunity.
Bitcoin has both with its volatility and mysterious creator.
Any global currency not overseen by a central or distributed (stakeholders) authority needs to be based on some sort of work to be scarce and neutral towards all the participants. I believe Bitcoin is a pure form of money in that sense.
The next step is getting rid of resource scarcity through technological advancements, in which case the idea of "money" and "economy" as a whole may no longer apply. How long will it take? Time will tell. But we are getting there
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