FIA did it to themselves with the supremely complicated hybrid MGU-H system. The same thing happened in LMP-1, manufacturers exited because of costs.
It also doesn’t help that the teams and FIA allowed themselves to go along with a formula that Mercedes had been toying with for a long time.
Honda North America is stayingwith the new Indycarengine formula because it’s a twin turbo MGU-K type system. With the spec hybrid unit costs become much more reasonable.
This same principle is happening in IMSA and WEC with the combination of American and European Prototype classes into LMDh and HyperCar top classes.
Motor racing is expensive, but trying to shoehorn road applicability into the formula is a recipe for disaster. Fans want noise, speed, and tangible fear, not quiet electric cars run on compact circuits at slow speeds.