What Is the Maximum Gas Fee a Front-Runner Would Rationally Pay for a Trade?

A front-runner would rationally pay a gas fee that is slightly higher than the victim's transaction fee, but critically, the total fee paid must be less than the profit generated from the front-running trade. The maximum rational fee is therefore constrained by the calculated Maximal Extractable Value (MEV) of the opportunity.

If the potential profit is $100, the front-runner will pay a fee slightly less than $100 to ensure a net profit.