Professional gamblers are more likely than amateur gamblers to meet criteria for problem gambling but minimal research has examined their gambling behavior and its consequences. This study compared gambling behavior, problem gambling symptoms, related harms, recognition, and help-seeking among problem semi/professional gamblers (PPGs) and problem amateur gamblers (PAGs). Surveys completed by 57 self-identified professional gamblers, 311 semi-professional gamblers and 4,226 amateur gamblers were analysed. PPGs were significantly more likely than PAGs to be male, younger, never married, speak a language other than English at home, and have higher psychological distress, compared to PAGs. PPGs were more likely to gamble more frequently on many skills-based forms, but most also participated in several chance-based forms. PPGs’ most common problematic gambling form was electronic gaming machines and they were more likely to have problems with sports betting than PAGs. Most PPGs reported coming out behind on all gambling forms over the previous year. PPGs were more likely than PAGs to report chasing losses and numerous detrimental financial gambling consequences. This group’s self-identification as semi/professional gamblers is clearly inaccurate and perhaps a means to avoid stigma, elevate status and support problem denial. PPGs may represent an extreme example of gamblers with erroneous cognitions and beliefs who lack the required discipline and skill to be successful professional gamblers. The findings identify a group of problem gamblers who may benefit from interventions to dispel their mistaken self-identity, and emphasize the need for more rigorous confirmation of professional gambler status in future research.