Napoleon’s fatal flaw was that he actually bought into that Royalty Nonsense.

I view Napoleon’s story as a hero’s journey. Every hero has a flaw - so they say. The obvious fatal flaw would be ambition but Napoleon was not ambitious in the typical sense. His ambition was to cleanse Europe from feudalism. But his flaw was that he bought into royalty. He wanted to merge his kind of Roman meritocracy ideas with royalty but that system was more putrid than he realized and it’s what brought him down. He underestimated what lies behind that mask. The poor Corsican gentleman as he styled himself at birth had fallen for that spell. They used that to destroy him. Sad but true.