Do any of the naysayers take into account the money being pumped into the economy because of bitcoin? I just dropped $500 on mining gear. Nothing compared to what others are doing. But still, $500 going out into the economy that otherwise would not have been spent.
But does that serve any real purpose? If difficulty increases by 100x because of all the new miners does that help bitcoins as a unit of exchange? All that equipment is basically wasting power to do arbitrary calculations that only have value because of an artificial currency. I don't want to sound anti-bitcoin or anything, it's just that argument reminds me of when people saying government spending is good because it creates jobs without considering whether those jobs add anything of value to the economy.