Pretty common. More than half of exchanges shut down, fail, or flee with peoples' money at some point.
Which is precisely why you don't keep any cryptos stored on an exchange.
This kind of thing is an obstacle in getting Bitcoin to be respected as any kind of mature item.
http://venturebeat.com/2014/02/14/f...hutdowns-2-7-million-theft-is-the-end-coming/
Now that doesn't mean that a lot of smart people weren't able to cash in on the craze and make mad profit while the getting was good. Smart people like that probably continually convert out of it at highs
That said, I wouldn't want to be the people who just ordered a bunch of $900 290X cards, or bought in at $600+, lol.
I honestly wonder if Bitcoin has another bounce left in it, or if the reputation hit is so vast that it won't recover ever to the full extent. I also wonder, and almost feel it predictable, that the speculators/investors who want to gamble on such things will (or have) move away from the volatility of Bitcoin to emerging coins. A de-coupling of Bitcoin from future coins would go a long way towards keeping the movement alive, otherwise if Bitcoin dies, they all die by association (not taken seriously by the business community, or worse : seen as a criminal enterprise by the Western governmental powers).