Bill
Your accountant is right. If you derive most of your income from gambling over a lengthy period of time the tax office will deem you to be in the business of gambling for a living. In other words a professional.They will ask you to pay tax on your earnings. You may well be successful in contesting the issue in court but that will not stop them from trying.I imagine the only ways they would be interested in the first place is if you declared your winnings to them voluntarily or if you used the gambling argument in an audit situation.
I did hear of a rort many years ago where a punter asked to be assessed as a professional and then submitted losing figures for three consecutive years. The story goes that the tax office knocked him back and he suddenly began winning and lived tax free from then on.Not sure about that one though.