Rampant apathy by an American populace more enamored with whores like the Kardashian family, Monday Night Football, and racial shit-stirring than furtherment of science, knowledge, and "local" shakedown of tools and techniques (moonbase) that will be necessary to take us beyond our finite little world. We are miserable, narcissistic, whiny little dysfunctional miscreants that would rather look for something to be offended by than look for ways to better humanity. We're riddled with faux-intellectuals that blather on with their heads up their asses disputing and denying scientific groundwork and accomplishment that's gone before us. They're no better than jackasses like Ted Cruz and the climate-change deniers. We haven't gone back because the best years of our miserable race are behind us and we're idiots raising idiot children where every child gets a star and excellence and success are offensive to the little snowflakes that tried so hard but just can't get it because society failed them.

That's why we haven't gone back and why Gene Cernan will unfortunately hold his distinction for many lifetimes yet to come.