Political predictions market

PredictIt is an online political prediction market. They issue a 1099-MISC (not W-2G) which calculates income as net profits minus their 10% fee on profits and minus their 5% fee to withdraw the profits. I expect my net profits this year to be roughly $7000. Minus those fees, the total comes to about $6200--which is what I expect PredictIt to report.

 

However, PredictIt charges a 5% fee on withdrawals for the principal as well as profits. While my $300 fee for withdrawing the profits will be included in the 1099, my additional $1500 to withdraw my principal will not be.

 

How can I deduct that additional $1500 from the 1099?