Abe Lincoln said "Most people are about as happy as they've made up their minds to be."

True. He might just as well have said, "Most people believe pretty much whatever they've made up their minds to believe."   ;-)

They are creatures of rigid mental habit. The only thing that can shock them out of a limiting mental habit is an actual undeniable experience that forces them to at least momentarily remove their blinders. Such an experience can change a person forever, but don't expect anyone else to change his habitual beliefs on account of it! Not a chance. The only experience that most people trust, ultimately, is their own...and that's not surprising. Animals are like that too.