Just as "make a bookstore" isn't the key to success, I don't believe you can say "pivot a lot" or "trial and error" is the key to success either. Plenty of startups pivot and run out of runway.
My current thinking is that a big piece of success is taking risks and being able to absorb the losses.
Generally big payouts don't come from a sure thing; you have to take multiple risks that could potentially have big payouts and survive long enough for one or more of them to pan-out.
True, this is a good point. The key to startup success is probably the same as the key to winning at Poker: win more than you lose :) Although I guess my point was just that I don't think Bezos thought that being a book salesman would make him a billionaire (as the article implies).
Ruthlessly identify and pursue existing capabilities that are profitable or that capitalize on or provide unique or rare market capabilities (which you can later try to turn into profitable areas), and always been experimenting to find more.
Right time and place, luck, skill and money in varying relative quantities. People focus on the skills, not unimportant by all means, but it is not the secret sauce.
So what then is the secret sauce?