It could be a defense mechanism. When you are in the public eye and a non-drinker or even a moderated drinker, you will have people asking you why you don't drink.
A male celeb might say: "I drank too much in the past" and then will be asked inevitably, "how much?"
If that celeb replies "Four beers per night", he is bound to be called a sissy and much worse. If that celeb were to exaggerate and say "two bottles of vodka before breakfast", people will make a face like this:
and he will be left alone and no further pressure will be applied.