I agree that if you want to persuade people and be successful in the business world, being the smartest person in the room isn't the most important quality. Being the loudest and most confident is. Just say your opinions as though they are obvious facts, and if someone disagrees, ignore them and say your thing again with even more confidence. I do not do this—heaven forbid, I'm too kind to do that—but it's the characteristic I see most successful people sharing... if success is defined as organizational prominence and compensation, rather than more trivial heuristics like a history of your claims coinciding with reality.