It actually takes surprisingly little if it's done consistently and without giving your body time to rest.

A standard drink has roughly 14g of ethanol in it. People with notable liver damage tend to have a history of a decade or more drinking 30-50 grams a day, or two to three drinks.
People who drink more than 80g a day for a decade are almost guaranteed to have liver problems (~5-6 drinks).

Obviously drinking a half gallon a day is worse, but consistent long term drinking is also not great.

It is essentially a poison that's only around because it's easy to make and traditional at this point.