This is a sign of gambling addiction. I read some articles before about this behavior where the person is in the "denial stage" where they can't accept they already addicted to gambling, as it is stated that he claims he does gambling for fun but in reality - he is already addicted. I know a lot of people like this, especially my close ones.
It's just sad because sometimes I want to talk and help them but end up they are angry because they are denying that they already addicted.