For a big casino, they might think deposit $10 and withdrawed $1,000 is still fine because $9,990 isn't a big lost for them because they've make more money than such amount.
But for a small casino, they might think $9,990 is a big lost for them because they only earn $100-$300 everyday, which mean they're need to work without getting any profit for 1-3 months. This make the casino will ask KYC and giving numerous excuse in order to not pay the winnings.
It has been confirmed many times, there are many ways to limit user who keep winning every day. The methods can be explored through scam accusation board as well.
Even though you/we keep saying this to read the Terms and condition we cannot deny that most of gamblers do not want to read the long text for sure they make immediately deposit once they see that the events or the bonuses in favor in their side and once they hit a jackpot makes a question once they want to make immediately withdrawal for a newly created account.
Terms&conditions are there for a reason, we can't say we didn't see this line or something like that to blame casino itself. Big winners don't have time to read whole page as well.