None of his theories are scientific. They're nice mental models to keep of the world, but they certainly don't justify his level of arrogance, especially not towards others who actually follow the scientific process to postulate theories
This is, by definition, a hypothesis that is both obviously true and also almost impossible to test. The very problem in question is that there is a fundamental lack of data on these rare events because they happen rarely.
No, they're "rules of thumb". Rules of thumbs can be great to make complex decisions (like in trading, as he does), but coming up with a few rules of thumb and doing well at your job does not warrant his level of confidence in his intellect.
It also common scientific practice to accept hypotheses within bounds of probability.