People believe what they want to.
I've spent a couple of years financing a business purchase. I spoke to a number of complete tools at banks but one of the more outstanding cretins I met was with a very well known Aussie bank. I got to the stage where I might have made it clear to the cretin that he was a cretin and then interesting stuff came out. My deal wasn't important because he had a meeting in a few hours with Elaine who was one of his 'major' clients. I was naturally totally enthralled that I might be meeting someone who mixed in such exalted circles and heard the biggest concoction of bull dust I have ever heard. It was clear that neither this idiot banker or his idiot client knew the first thing about airlines, or indeed even selling a bag of mixed lollies at a school tuck shop. It was sickening to listen to.
Bankers etc 'want' to drink idiots Kool Aid because their bonuses depend on them believing it enough to convince their superiors to get their deal across the line. And as one smart one told me 'It doesn't matter if you turn out to have been wrong, as long as the argument is strong enough to hold water when you present it'.
Castles made of sand. Like subprime, the piper will need to be paid. And it's not the frauds and idiots that cause the problems who end up paying....