Hamster wasn't saying that everyone has problems with drinking or drug abuse, but in general there is a high instance of abuse. In fact, according to the National Institute of Alcohol Abuse and Alcoholism, 60.7% of people diagnosed with Bipolar I have a substance use disorder and 48.1% of people diagnosed with Bipolar II have a substance use disorder.

http://pubs.niaaa.nih.gov/publicatio...-2/103-108.htm

Statistics like those are why people tend to assume that people with bp are using either drugs or alcohol. Combine that with the fact that a lot of people are not going to come out and say, "I have a substance abuse problem", and you have a situation where professionals, at times, have to pry and maybe assume when they wouldn't with the general population.