Selling cookies helped me to realize that you needed to have a certain way to communicate with people. You also needed business skills. You knew you needed to sell a certain amount of boxes, so that gave me some business sense.
Only when Stephen Strange has his accident and everything that he's ever had in his life falls apart that he becomes pretty monstrous. It's the self-loathing rage of a wounded animal and he doesn't have a coping mechanism at all. It ties in with the discipline and the magic of this world.