I don't really know if similar question or concerns has been raised before, we often say that we are gamblers but does it mean that anyone who gambles once or twice is a gambler? If no, how long could someone be classified as a gambler or what games that are to be classified as someone gambling.
Betting once or twice in your life doesn't make you a gambler. Even if someones buy a lottery ticket every New Year's Eve for 20+ years doesn't make him a gambler. We can consider someone a gambler if they bet regularly, like every weekend, no matter the amount.