i am a gambler of course but i don't even really think that i am a gambling expert, because when one person is expert in gambling you would not lose anymore, gambling is risky and no one could be expert in gambling it is when you are lucky or bad luck when you gamble.
Gambling expert is not someone that does not lose but someone that can make money in constant basis. It is the same as trading expert because if you are an expert, that means you are most likely going to make less mistake then most people. That also means your chance of getting money from gambling is higher than most people
And I don't think it will be hard for us to distinguish by ourselves alone that we are expert, unless we do really get a huge winning whenever we play, expertise may vary in experience through lose and win and on how we react over it and I think only in movies we can see those still cool when they lose too much.