Trawling through the various cesspits of peak oil doom boards, I've noticed a common thread. Many of the biggest and most vocal doomers are Druids, Animists, English Teachers, Accountants, Lawyers etc. In other words, functionally illiterate in science.
I reckon this must be the reason why they swallow olduvai "theory" (what a joke) whole and when confronted just regurgitate like big roaches. They breed too. Wherever you get a treehugger more are attracted.
Another type of person attracted to dieoff type theories seem to be those who long for the destruction of modern industrial civilization and actively promote gibberish such as back to the land. Careful not to say "we will die without fossil fuels" and "if we go back to the land all will be well" in one breath.
One particular recent example of this was a comment on a new scientist article regarding Hansen's global warming piece. This clown said (paraphrasal): "What would be wrong with that [dieoff of all humans]? At least the ecosystems would be given a chance to recover." That particular clown hates human beings and would see no problem if humanity went extinct. That's disgusting in my eyes but the hippy/treehugger/global warming crowd are replete with these people.
The reason for that, I suspect, is that anyone with the ability to see through rhetoric and who has at least a sophomoric grasp of deductive reasoning can see that they
1. WANT civilization to fall (and anything that says it will is to be pounced on with great glee)
2. WANT a dieoff. (all will be well - with the environment, just not the human population)
It's a bizarre way of thinking but often underneath there is a longing for the "good old days". For those who go further and want extinction, there is nothing less than a total hatred for humankind.
Too late people, the genie was out of the bottle when we invented agriculture.
There's no way we're getting off of the tiger.