Not sure about this list. I expect some of the great writers weren’t naturally talented and had to work twice as hard to make up for that. Some were so naturally talented that they didn’t really need to work very hard. Seriously doubt they were all hard drinkers. And quite a few only became great writers long after their deaths; in their lifetimes they met with little success but some of what they wrote was just barely successful enough to be kept around for a later generation to discover them and proclaim their greatness. Basically, their stuff became a cult classic of it’s day only to later be declared great literature.