I'd imagine most manic episodes are temporary and followed up with depression (so Bipolar). Also people with legit Bipolar are often found to be more creative than average, regardless of their depressive phases.
It's not about working hard, but working smart. Most "go-getters" probably either have a natural born talent (or intelligence) and/or were raised well with (potentially strict) parents who instilled a strong work ethic in their children... I also think that most of those who are extremely successful (billionaires) were either born into wealth or had special connections that gave them the upper-hand.