I have a contrary opinion: most important things are started by apparently small things, but there is a huge amount of training, effort and persistence behind getting to that small thing. Zuckerberg was a serial entrepreneur who already made a few successful websites/apps before Facebook, Nvidia spent decades becoming the world's best GPU manufacturer (when they started there were ~300 graphics processor companies), etc etc.
Since we're talking about books, this statement reminds me of one that OP might want to look at: Super Founders.
It's been a while since I've read it, but off the top of my head: most successful founders are older than you probably think, have less industry experience than you probably think, start (like nVidia) with more competitors than you think, but (to your other point) are more likely to have more entrepreneurial experience than you think (even very young famous founders like Zuckerberg or the Collisons had another venture before the one that made them very well known).
Honestly I found Super Founders kind of dry, but it's one of the only data-driven books about what differences exist between founders of businesses with exception outcomes vs founders with less successful outcomes that I've read.
One thing I've noticed working with successful people, is they consistently have a track record of success. Even when its non work related - for instance being very high level in a competitive video game. Being personally interested in both business and hobby success, I see this across so many disparate activities. Successful people tackle their pursuits with their heart and soul, but are also smart about what they do, who they learn from, who they surround themselves with, etc.
