Personally I have played on Rollbit several times and doesn't got any problem with the withdrawal, probably this is due to technical error about their internal system. I will keep playing on Rollbit and let's see how it goes about the withdrawal.
when players play normally, withdrawals will not have problems, maybe that person faced that because they couldn't wait for the funds to be processed so he immediately made a thread because this involves large funds, so it's only natural that Rollbit needs to be careful in handling it, good thing everything can be resolved and Rollbit's business is worth more than the funds withdrawn by that person so there's no way Rollbit will damage his reputation that they has build so far.