"Successful people create companies. More successful people create countries. The most successful people create religions."
I heard this from Qi Lu; I'm not sure what the source is. It got me thinking, though--the most successful founders do not set out to create companies. They are on a mission to create something closer to a religion, and at some point it turns out that forming a company is the easiest way to do so.
In general, the big companies don't come from pivots, and I think this is most of the reason why.