Another possibility if a profitable bettor keeps on winning and just taking the bookies money away and keeps on cashing out. They'll surely be noticed. I've seen bettors that have been in that state and they got banned and kicked out of the casino so they have to find another one. That's why telling that they've got sure and winnable tips, they apply and use it for themselves and they'd for sure going to be rich no need to do these offerings to the others trying to milk from their money, it's simple as nursery.
This is pathetic and is not happening in betting only but in all risky activities online that gives money. The reason why this is happening is due to weak regulations. Are you tell me that you can take all my money when I lose but you will not pay me but kick me out when I am winning? What is fairness in that? No country's law or lawsuit will ever side the company, it's very bad.
That's business and that's it.
Casinos will always take the advantage that they want to have. And the process of giving the money to the rightful owner where in fact that's owned by them, it's the same concept as the banks. They want verification.
However, the issue is lessen or even eradicated if you can gamble with a trusted and well-capitalised casino with a huge customer base. They are making millions of dollars per day from the losers, so if you are making merely $1000 or so from them daily, they might still look away, especially when a winning situation like yours is uncommon.
It is about our choices, so we choose to gamble in reputable casinos that has less issues known to something such as withdrawals.