Withdrawal of winnings isn't just the issue because you can withdraw your winnings and then still put the money back in it again because maybe you actually didn't use the money well the way it's supposed to be used. There are so many cases that have resulted to gamblers getting all addicted because of the lack of will power to actually make that decision of yours withdrawing their funds and using it wisely.
I've always maintained that withdrawal may be good but certainly not the ultimate to know the real success of a gambler unless the gambler can be withdrawing consistently and also have more withdrawals than the deposited sums. This is the only situation where the gambler can reference the withdrawal as a basis of their success. And of course, the withdrawal will not happen without good gambling skills, habits and management because, if these are lacking I wonder how the gambler will be able to be consistent in the withdrawal. Such a gambler may be lucky at first but certainly will have issues with some consistent gambling and nothing is successful in gambling if the gambler consistently deposits and loses his money despite making some withdrawals.