"Making money with rebates, working without rebates"
Both of you trade for a day, you earn 200, he also earns 200.
He gets an extra rebate of +40 U, leaving you with a net profit of only 160.
While you are still figuring out how to break even,
others rely solely on rebates, saving back a whole set of principal from the fees.
Don't forget:
Smart people rely on rebates to recover their losses,
Smart platforms survive on your transaction fees.