I feel as if this could be exploited, I think this is very much like the Gas Refund Proposal though. I would say for users with a small folio the GRP is the optimal solution but a trading competition would be cool. Maybe award the winners based on percent gains made through April using paraswap with a minimum size wallet to prevent abuse.
I actually have been working on a lottery idea, where part of the payment/fee’s are used to pay everybody indefinitely so everybody would earn their buy-in/ticket back within at least a month or three/four and from that moment on earn (even how little this value may be, but this also depends on certain other aspects and have found ways to alter this).
I get allergic from the word lottery, especially those like Pancakeswap etc.
Whenever you add a lottery to your platform; you better be funny.