The worst thing you can say about libertarians is that they are intellectually immature, frozen in the worldview many of them absorbed from reading Ayn Rand novels in high school. Like other ideologues, libertarians react to the world's failing to conform to their model by asking where the world went wrong. Their heroic view of capitalism makes it difficult for them to accept that markets can be irrational, misunderstand risk, and misallocate resources or that financial systems without vigorous government oversight and the capacity for pragmatic intervention constitute a recipe for disaster. They are bankrupt, and this time, there will be no bailout.
This perhaps paints with slightly too broad a brush, though it is certainly applicable to the Rand fanatics.
(Thanks to Jerry Dworkin for the pointer to the article linked above.)