It is extremely common. I forget the percentages.
Include me in that group because I am a recovering alcoholic.

Addictions can often mask bipolar symptoms because people are self-medicationg.
In AA and NA you encounter a very high percentage of people with bipolar disorder.
Many people have more than one addiction, and a lot of times when one addiction is cured/in recovery, another one replaces it.

My father is an alcoholic and gets himself into a lot of trouble gambling when he is manic. In the past, he had the habit of buying and selling houses and cars on whims during episodes, too.