i always get the feeling speculators are driving most of the value of these currencies (in the case of these ico it's pure speculation) but that one day when people start to execute smart contracts and make good use of the currency a more true value would start to show and maybe the $ value will stop fluctuating so wildly. (this would be after mainstream adoption though, and we have a long way to go). i too am guilty of speculating..i bought tezos and eos for that reason.
value is subjective. Because of all the speculation, it gives off the signal to some that crypto currency is a ponzi scheme..at the same time, the currency itself when adopted provides value.