I've done this plenty of times. It's a common risk in cold climates when tractors, cars and lawnmowers are parked outside and one forgets to drain the tank. It gums up the carburetor. So you rebuild the carburetor, which takes 1 hr and $5 to do at home, or $100 at the dealer. Not $40,000. It also doesn't "destroy the engine". There is a high probability either don't know what you are talking about and made that claim up, or you are intentionally being misleading in order to promote a viewpoint using false claims.
First off most cars build after the 1980's don't have a carburetor and generally use fuel injection. Also, to much water in the tank can easily lead to a blown head gasket among other things.
Second most cars don't cost 40k, but if your talking about a say a bugatti veyron it's not that hard to do 40k of damage. If you want to compare it to the cost of the car then for an older car having a few thousand dollar repair bill can easily cost more than the car is worth.
