A lot of the people I have met with ADHD find they prefer to have a job where they can move around and have different customers/jobs, they are often in sales or construction and even in the fishing industry where they go different places to fish. My husband is in construction and he likes it because he works on a job and finishes it than goes someplace else. It's very similar to the pattern you describe only where you get bored and quit, and go someplace else, he doesn't quit, he just finishes a job and goes someplace else.

The thing with ADHD is not lack of intelligence, often many even have genius IQ's, what it is is lack of patience to focus on one thing over and over again. They literally get bored, they like motion and change.