But he is USEFUL - the less people will get into mining, the better for those that will.

Now, another thing to think about - different locations on Earth have different electricity costs. Mine is about 1/2 of the US right now.

Then think about solar and wind power. Yes, if we were not all enslaved by the Govts., then we could just sell the electricity in the open market, but with millions of regulations and high entry cost - it's not as easy as Bitcoin mining way to convert electricity into some personal power (a.k.a. money).

Third point - it's just FUN. People are playing on the stock market in a WAY more hostile environment, geared to cheat and rid small players of their money. Bitcoin scene is very refreshing after THAT. And, yes, investing $15,000 you don't have is probably not a good idea, but investing $1000 certainly is (just think about all these loosing tens of thousands of USD on futures and Forex).