ADHD and all of the other so-called interrelated "spectrum" disorders like autism, OCD, and yes, even alcoholism, are simply one end of the normal bell curve distribution of human behavior. Nowadays doctors draw a line at one point and say, "beyond this point is xxx disorder," but it's nowhere near that simple. It's not even a line but more of a multidimensional surface that defies any simple boundaries, but computer records and insurance companies require a 0 or 1 (no or yes) answer.
Yes, some people need chemical assistance to live their lives, but other simply need to learn to understand and live with their personality, like taking the time to look at something shiny off in left field when the situation allows it instead of an OCD-like focus on the task at hand. Indeed, those tendencies can be an advantage in some situations... being easily distracted might just save the hunter in a forest full of dangerous beasts, or a daydreaming engineer who suddenly thinks of a new solution in a different direction.