ADD can actually help some people be successful.
There are lots of entrepreneurs that will tell you that they are successful, largely because they have a very active imagination; they are attracted to novelty, they have an experimental streak where they are willing to try new things, and break previously held limited beliefs or glass ceilings. A lot of progress in our culture is, probably, attributable to people who are ADDish and were willing to forge ahead and try new things.
The drawback, of course, is does mean that we need some tools. I teach a lot of workshops and classes designed to help parents teach their children how to harness this wild horse of a brain they have. Otherwise, it can be very, very difficult to function. But when it's harnessed, when we are really managing that tendency to be many places at once or to focus on many things at once, it can really be a tool to have an interesting, stimulating life.
I am diagnosed ADD. I think it's contributed, in many ways, to the success of my life, and certainly, the enjoyment of it.