It is normal, sometime gamblers are not patience enough in such situation, so they decide to continue gambling while waiting for the withdrawal issues to be fixed. Unluckily, players lost the money at this stage because they might be a little bit angry and lose their control.
It isn't normal actually. Even the biggest losers in the gambling world manage to acquire a small portion of their winnings despite losing the majority of it due to their own greed and stupidity. This is why it's tough to believe op in this case.
I guess OP got impatient and gambled, resulting in him losing all the money he previously won.
Or this could be a fabricated story in order to help promote this casino which is a smart and risky strategy. Another weird thing I noticed is that he hasn't been complaining about the site refusing his withdrawals after losing his entire winnings.