I stopped after the first paragraph: If you wanted to get rich, how would you do it? I think your best bet would be to start or join a startup. That's been a reliable way to get rich for hundreds of years.

Come on. Startups are long shots, a gamble, definitely not a reliable bet. Most startups fail ( http://hubpages.com/hub/why-startups-fail ) and very few are massive successes. It's the rock-star model of getting rich - many try, few succeed.

Was a "venture-backed trading voyages of the Middle Ages" a "reliable way to get rich" ? There were pirates, the danger of sinking the ship in storms or on rocks, scurvy, unpredictable conditions at the other end of the voyage etc... basically it's high risk, high reward.