Missing 411 critics always refuse to look at unusual cases with strange evidence, and always make blanket statements to dismiss everything at once. They say "it's just children wandering off" and ignore the adult cases and when children as young as 4 are found 2000 ft up a mountain. They say "it was just a bear/cougar" even though these animal attacks leave a fuckton of evidence like blood, prints, remains, droppings, clothing fragments, etc. A bear doesn't just swallow a hiker whole like a damn anaconda.
Lastly, and this is a wider problem with people today, is that skeptics are so materialist and aloof that they reject the notion that anything outside their very narrow framework of mind is not real. Science is now only beginning to move beyond the newtonian. To assume we know everything about the universe with our limited means of observation is incredibly ignorant.
My personal belief, not from missing 411 but reading Jaques Villet and John Keel, is that there are nonphysical entities which exist on some parallel realm to our physical reality. These entities can interact with us and appear in different forms, and have been called many things over the years, like the fey folk, demons, ufos, etc. Their motives are a mystery, but they seem to take some interest in humans. Read stories of the fey taking humans to their unseen world, it absolutely parallels the conditions of missing 411. You may think this is a loony schizo belief, but I did a lot of reading to get to this point and I would say there's a lot of compelling evidence to suggest there's some kind of intelligence out there that interacts with humanity, for good or ill.
Also the idea of a flesh and blood bigfoot is completely ridiculous. No way a large physical ape can survive in north america this long without evidence.