What Role Do Gas Fees Play in the Profitability of a Front-Running Attack?

Gas fees are central to the profitability of a front-running attack. The attacker must pay a higher gas fee than the victim to incentivize the validator to order their transaction first.

This higher fee is the cost of the attack. The potential profit from the front-run (e.g. from price slippage) must exceed this additional gas cost.

Therefore, front-runners engage in "priority gas auctions" (PGAs), where the winner is the bot willing to sacrifice the largest portion of its MEV as a tip to the validator.