He obviously refers to gambling as an activity involving playing games based on luck (like dice)

And humans are bad at this type of gambling because they are just bad at probabilities. For example, people easily confuse plausibility for probability, i.e. they erroneously believe that adding more details about something necessarily makes it more probable, while in actuality it only makes it more plausible (read, more easily believable).

Regarding your examples specifically, they are not reflecting the law of small numbers, and I could go so far as to even say they have nothing to do with gambling as such. People became able to cross the oceans after they had discovered the power of the keel. Good luck to you trying to cross an ocean on oars alone (as that would be gambling)