Why Bitcoin is a Stock, not a Currency

Bitcoin is a tulip, not a stock:

http://en.wikipedia.org/wiki/Tulip_mania

Well, I suppose it could be considered the same as a penny stock being pumped and dumped. I feel slightly sorry (in advance) for the people who lose their life savings when the bubble bursts, but not hugely sorry, as it will have been greed that led to their downfall, and my capacity for empathy in such cases is limited.