Beer. People stopped being nomadic when there were all of the ingredients and technology in the same place to brew beer. Then they didn’t leave because if they did there was no beer there. So they stayed near the beer.
Consider that beer is safer to drink than the sources of water that were available, and the pleasing intoxicating effects. Possibly also the alcohol addiction to an extent.
https://www.nytimes.com/2013/03/17/opinion/sunday/how-beer-g...
Excessive consumption causes Fetal Alcohol Syndrome, but there is no sharp cut off.
Nobody likes to talk about it, though.