Louder than logic

Why is rhetoric always louder than logic?
Recently I read 'Blink' which says something in context. It is not the quality of an idea, which makes it popular. An idea, a philosophy etc. may be adopted by many, despite being wrong, evil or downright stupid.
It is probably understandable that people in general are moved and driven by such ideas (in fact to understand it better read' the tipping point'). It is tragic that often those who wear the mantle of being the experts, the intellect of the society state opinions expressed as obvious truisms when actually they are pure and unadulterated rhetoric.
Weren't the dot coms of 1999,2000 amazing ideas which will change the world according to many intelligent people(some with MBA degrees from IIM A, Harvard, Stanford etc) . Wasn't Enron one of the most admired companies in World according to Fortune, a year before bankruptcy.
The lesson from these is that an argument backed by logic which needs least 'quantity' ( not just no. but overall how big or small these assumptions are) of assumptions are safer to go with than opinion of 'Experts' .
This is precisely why people like Dhirubhai Ambani, Richard Branson etc., without a MBA degree have been so much more successful than many others with one. Because, logic is more powerful than 'expert opinion' and that's what they are driven/guided by.