If I had a bitcoin for every person I've met in the past six months who told me that bitcoin is a scam, I'd be a rich man. Or a poor one, depending in which day of the week we're talking about.

Watching the exchange rate for bitcoins over the past month has been like seeing the outline of a roller coaster on the horizon. On Jan. 7, for example, a bitcoin was trading at $934; by Feb. 27 it was down to $528; and on March 5 it was $678. So I guess that if you were "investing" (i.e., speculating) in the things, you'd feel as sick as any Fuji-Q Highland customer on a bad day.

But here's the really strange thing: While "normal" people — and many mainstream journalists — seem to think that this bitcoin stuff must be some kind of racket, some of the computer scientists and hackers of my acquaintance think it's the most interesting idea to have come along in ages. And in a way, that discrepancy may be the key to understanding the phenomenon.