I find those smart choices don't come to mind as easily as the missed big opportunity choices, so I have to work to keep them in mind too.
Is the success of an endeavor highly sensitive to small perturbations in the timeline? I'm guessing most of us don't buy into the mythology of the all-powerful Idea and Founders. Every employee and action matters. The details matter. If I could go back in time and swap in for employee #8 at MS, it would probably no longer be the MS we know. Or perhaps we wouldn't know of it at all.
Perhaps best not to sweat these missed opportunities, and instead keep making whatever we're doing right now the next MS, or whatever you define as outrageous success.
It may later seem like it was a loss, so some form of retrospective loss aversion might be more appropriate to apply to this phenomena: http://en.wikipedia.org/wiki/Loss_aversion
On a general note wrt. failure/success then we actually tend to slightly exaggerate our successes when remembering them, and similarly downplay our failures.