Personally, I think there's plenty of blame to go around to everybody.
I lived there for a long time myself. I heard the warnings, too, and always kind of brushed them off being too concerned with my petty crap (school, finding a job, keeping a job, etc.). I never even paid much attention when the occasional hurricane did pop up, because I'd been through so many as a kid and nothing much ever happened (at least not to us...Camille and Andrew were just things on TV).
Then I moved away and it all became even more of an abstract concept. Yeah, someday California will fall into the sea, someday we'll have a big terrorist attack in New York, someday New Orleans will be blown away, etc.
Then one day, something actually does happen....