PSA: If you're already caught up in this and don't know how to stop, or can't stop, or are in too much trouble to believe that you can ever be normal again...PM me. There is hope.
Taxes are a massive headache and take away from any MS benefit IMO. You need to pay taxes on all your winnings, and you can not use the losses to offset. There is a possible way around it (sessions), but this workaround hasn't been challenged yet in court and no guarantee that it will hold up. You can also file taxes as a professional gambler to circumvent this, but that's a whole can of worms too (hard if you have income from other sources).Long story short, speak to an accountant who's very knowledgeable in gambling, especially matched betting, before doing this. I did some research into it and this is what I came out with - the tax headache is not worth the play.
OP made 125k discover points by loading and withdrawing. No wagering necessary if you are ok waiting 3 days. No taxes.