Bottom is maybe when things are bad enough that your desire to make a change and not drink exceeds your desire to keep drinking. It is pretty common to see people talking about wanting to quit drinking, and then they keep on drinking or relapsing. Desire to drink has exceeded desire to not drink.
I assume that drinking is invariably a volitional act, because the only time I've ever seen people drinking non-intentionally is in those old Warner Bros cartoons, where someone is at death's door lying in the snow and a big Saint Bernard runs up with one of those "XXX" barrels around its neck and GLUG GLUG GLUG pours some in the guy's mouth and he is magically revived.
That stuff doesn't happen in real life. Because Saint Bernards with booze jugs around their necks are like unicorns, man .. I looked for one for years and never found him.