I'm having a tough time trying to imagine a job where being a poker player would give you a competitive advantage over other candidates for that job.
It would definitely not be a smart thing to do for 99% of the jobs you might apply for. And just putting self-employed won't work either - a good interviewer will want to know the details of that.
..but leaving a big hole in your employment history will also cause a good interviewer to ask for details...
Tell them your a self employed equity trader.