According to what I've read most gas stations make very little profit if any on gas sales. It is the things they sell in the accompanying convenience store where they make their money.

An average ICE "charging" at a gas station adds mileage around 15x faster than the fastest charging EV at a Supercharger. If you convert an existing gas station location to an EV charging station that means that the number of cars you can handle per hour goes down by more than an order of magnitude, which means your convenience store sales will go down.

The convenience store sales probably won't go down by an order of magnitude because there are usually a significant number of people who come just for the convenience store and don't refuel their car. Still, I'd expect that at a lot of locations that drop of in convenience store visits from people who are there to refuel will be enough to make that location not profitable.