I can tell you that if you are a professional gambler in the US, you pay normal taxes (15%-30%) based on your tax bracket, etc. You can also deduct losses against wins, and also travel expense, computer costs, etc. But to be considered a pro most of your annual inome must be derived from gambling.

As a casual gambler in the US you must claim all wins and losses and deduct losses up to the amount you won (so you can’t report a loss at year end, just "0") As a casual gambler you must pay teh highest tax rate for capital gains — 30% and cannot claim expenses.

The best place to be a pro or do arbitrage is England — no taxes on any gaming wins! Might be the same in Canada — just dont know.

As for arbitrage it is absolutely impossile to make a consistent living at it. Too much software out thre now and too many people doing it — they get snapped up immediately, and when they don’t the arbs are usually at sportsbooks you may not have an account at.

Good luck!
References :
I am a professional gambler.