I look at motivation as the hind-sight rationalization for how people got lucky. For all we know, 30 other people were trying what DHH was, but we never heard from them because they didn't get lucky.
I do think you can stack the cards in your favor (DHH is a really smart guy, that is certainly one planted card), but no amount of internal anything can guarantee success.
So I try to stack some cards: work regularly on my project, make a concerted effort to find value to add, interact with people in a positive way so I don't burn bridges, etc. Maybe it's not an "I can remake the world to be what I want" entrepreneurial attitude, but I think it is more realistic for a bootstrapped project.
If he had initially framed his racing goal as winning Le Mans, he might have said "You know what, this Rails thing is going pretty well, why don't I just stick to that."
And if he had initially framed his goals for Rails as "creating a popular new framework", he might have said "you know what, XBOX is pretty fun", and never tried.
I've no doubt that DHH has failed at some goals using this method. The important thing is that it has helped him try enough times to rack up successes as well.