Idiocracy always had a weird eugenics undertone to me. That undesirable people will out procreate desirable ones.

That's the face-value pitch. American troglodytes keep breeding while the "good" people self-select into oblivion.

But I'd argue a funnier reading is that liberal intelligentsia produces sexless weirdos and losers more concerned with personal vanity and careerism than building a future they might actually want to live in. The run into a hereditary dead end as the American consumer culturalism they seek to master basically kills their libidos.

The David Duchovny movie "Evolution" handles this issue a bit more gracefully, as the things rapidly breeding and spreading are alien lifeforms rather than American chuds. The climax of the movie has the protagonists fighting a fifty foot tall alien amoeba. Duchovny's character bemoans how evolution doesn't favor any particular trait beyond habitat suitability and muses how sometimes the simplest organisms are the best positioned to thrive.