I can see what you're saying, but I don't think that this is a problem with cryptocurrencies specifically, it's a problem with buggy software, yes, but it's something that is the case with every dangerous exploit being actively taken advantage of in the wild, Heartbleed would be an example that doesn't involve cryptocurrencies, but I give you that the Ether-based ecosystem seems to be a particularly buggy collection of software, probably because of too much ambition, (a Turing-complete VM), being written by people with too little experience and applied for very sensitive (monetary) transactions, which seems like a recipe for disaster.