I never said it was true, and it is certainly for entertainment purposes as its primary focus. If you were to summarize its predictive nature, it would result in a one sentence statement. Brave New World and 1984 are better in their predictive aspects, but I was not comparing Idiocracy to them. I was primarily comparing it to The Time Machine and well... to itself in a way. The intent of the movie was not as a documentary on the condition of humanity, but as a plot device, it can serve the purpose of warning us of the danger of thinking we can predict everything when we cannot predict much of anything at all.

I haven't actually seen Idiocracy, but I know enough about it to recognize that (a) like most SF, Idiocracy is a commentary on the present disguised as a commentary on the future; (b) The folk theory of demographics embodied in Idiocracy (together with the time machine, of course) is a framing device, designed to give us an excuse to adopt a ridiculous perspective. It's a deliberately silly theory, just as Beavis and Butthead were a deliberately silly representation of the average fan of MTV in the 1990s.