Borderline FUD
I'm not much of a believer in coin, but this is some pretty weak sauce.
First of all, a great number of the coin hacks have been because people don't understand security. Wallets getting stolen, or their owner being threatened with catastrophic loss of blood, are not failures of coin in any meaningful sense. Exchange owners scamming out is nothing but old fashion commodities fraud. It's not until you get into exchange hacking and/or "smart" contract exploits that you are talking about anything particular to coin, and I would argue that most or even all exchange hacking is no different than hacking of any other commodity exchange being hacked.
The difference, then, is almost entirely down to a lack of professionalism and/or threat awareness.
The one remaining hacking issue is "smart" contract exploits. Yes, this is a big and unique risks. And it would be almost nonexistent if the safe arithmetic operations were cheap instead of the unsafe ones. So yes, Etherium has a serious problem because it failed to define a VM that was safe in default mode for certain core operations.
I remain highly skeptical about the dangers of deflation for currencies that are divisible to the extent that most coin is. I think that the mechanics are quite different.
Far more serious to me are the fact that these markets are so small & thin that they are highly volatile & easily manipulated. Furthermore, if they ever DO get large enough to be considered a threat to the fiat currencies, less than 1% of the US budget and you set up enough mining rigs to own a majority. Oops.
Speaking of the fiat issuers, until you can keep the soldiers off your lawn by paying in coin, don't bet against the fiat currencies.
Biting the hand that feeds IT
