What causes alcoholics to drink alcohol to a fault, and be cantankerous in the first place?

Is it a rough upbringing? (The last thing I would EVER wish upon anyone is a rough childhood!)

A sudden death of someone loved and held dear way too much? Firing from a job?

Whatever caused their cantankerous alcoholism, would you please share testimonies of anyone you knew who came to be alcoholics who get enraged at the drop of a hat?

What is their chip on their shoulder?
How would you suggest that they get rid of said chip?

Moreover, if someone is an alcoholic but keeps a hospitable, slow-to-anger personality, how do they do it?

(By the way, if you are an alcoholic yourself, please don’t be shy; share your testimonies too! That is often the first step to recovery.)