Investment Banking. A professional gambler in all but name.
It actually doesn’t pay to be a “Professional Gambler” in the self-employed sense in this country, because in UK law all gambling returns are tax-free. Why “Go Pro” and pay whatever taxes would be required when you can keep the winnings “private”, and get them tax-free anyways?
Sure, you wouldn’t be able to claim tax offsets - BUT you’re not going out there hell-bent on losing money - right?
(In my futures broker’s sign-up blurb, there’s an extra form that has to be filled in if you actually wish to run your trading account deliberately at a loss… so don’t assume anything is black and white in the Casino Banking world!)