It does not have any benefit, and that was the point. Somewhere in the past someone took a drink after they were bitten, and they didn't die. As Max stated, many snakes will not waste the precious resource of their venom on something they do not plan to eat and are just trying to scare you away. So many snake bites are not injected with venom. Correlation is causation in the minds of most, so they determined that alcohol is good for snake bite. At the very least, it may calm someone down and slow down their heart rate, which may slow the spread of some of the venoms.