For lots of reasons. Often just something that developed over time by going out with friends, to emotional issues such as work pressures, divorce etc. and sometimes the thought that the only way of having a good time is to drink.
It tends to become a crutch and yet like all people who drink too much there is that wish to be in control. We will be working on any emotional causes behind the drinking but also working with your subconscious mind by changing beliefs and habits.
Binge drinkers are frequently the centre of attention which at some point may have been ok but now stopped to be funny. By letting go of an old habit you will also be able to rescue your reputation and feel better about yourself.