I don't chase my losses but rather just enjoy every single bit I have to gamble. Most of it comes from freerolls that are present in these gambling sites. Never deposited any btc in gambling sites but I still somehow come out as a winner. 
That is good for you. But how can a casino site make a living out of you?
. There are too many on line casinos. Maybe some of them are not designed properly. So some gamblers will always win there.
Yes its true they will win but not always, if they always win Im sure they will keep on playing again and again until one day they will lose it and start to deposit more and more and in the end they will lose all of it. Most gambling site will earn from this kind of strategy I dont know if they have any good method to earn or not