I lost money to Mt. Gox, but filing a lawsuit won't get anyone anywhere. Want to see a sad pdf? https://www.mtgox.com/img/pdf/20150202_tibanne.pdf
Sad for the customers. Not for Karpeles, the owner of Mt. Gox. He's still a millionaire and still free, and might even have the customers' bitcoins. No one will probably find out.
I know you're talking about Bitcoin startups founded in the US or EU, but the same applies: If the startup goes bankrupt, the customers won't get anything back. There's nothing to get back except empty coffers.
We have courts and bankruptcy laws for a reason.
You're now a millionaire, and no one can ever take that way from you. No court matters. As long as the price of bitcoin doesn't go down by more than 10x, you'll still be very wealthy. And no one can prove a thing.
This is business as usual in the bitcoin world. Bitcoin has made it very easy to separate people from their money, and courts have no power to do anything about it.
Would you go to prison for a few years to be a millionaire? There is no shortage of people willing to risk this.
As you can see from the rest of the thread, people are willing to believe almost any cover story, no matter how implausible. Even that an exchange could be DDoSed by search engines.
When you're transacting in something of value (whether that be money, digital currency, or pokemon cards) for your users, you better be sure to take it seriously.