The poker room theft.
Betcoin previously withheld 43 bitcoins — over $5 million and counting — from their poker players. The case is publicly documented and is the largest single piece of evidence that this is not a one-off incident but a recurring pattern: once a balance grows large enough, Betcoin is willing to withhold it.
The handling of the poker room failure has been characterized publicly as a result of incompetence and a refusal to pay out a bad-beat jackpot that had already been accumulated by players.