Filing as self employed, or as a business are 2 of the options, but not the only options. Obviously not the best option for me. I don't want to get into suggesting any kind of tax advice, I'll leave that to tax specialist and my guy is THE gambling tax specialist here in Vegas.
For the short of it, in the last 10 years I have had a year where I made 27k and a year where I made 140k. So happens they were back to back. Both were extremes for me. I wouldn't want to use either figure to pay estimated quarterly taxes for the following year. One would have me owing a bucket at years end while the other would have me overpaying and I don't want the Government "holding" my money either.
Fortunately in recent years, the IRS has come to realize the uniqueness of professional gambling and has allowed for other options.