Maybe we see why other people or non-gamblers can identify much faster if one is already addicted because they see behavior that a gambler might think is normal or simply immune to. A gambler might be so immune to losing he doesn’t realize how bad it has become. Subconsciously maybe why they hide their gambling habits is because they know that others will be able to recognize harmful behaviors.
Of course, a change in behavior will be easily discernible from the volume of play. If he plays almost 20 days a month, he's definitely at a high level of addiction. But if he only visits once a month, or even not at all, it means he's just coming, playing, and looking for fun.
No one is immune to the stress of a losing streak and doesn't regret it at all. My assumption is that he'll come back to play to try to turn things around, even if he loses again. But what makes him great is his strong desire to cover it up, even if it's funny that he ends up losing again.