Surely currencies are nothing but tools for exchange, and their value is as a medium of exchange?
I see "bitcoin" as a currency not too unlike I see "paypal" as a currency. That is, not particularly.
Why foolish? Risky, but not necessarily foolish. The bitcoin exchange rate has been going up all the time. Even with simple strategies such as dollar-cost averaging you would probably have done pretty well within the last couple of years.