There are several reasons why the educated people of Charles Murray’s fictional Belmont don’t convey their better values to others and don’t judge others who fall short.
To begin with, there is the general stricture against any kind of judgment or “preachiness” in our culture today. Everything has to be carefully worded to avoid any sense of blame or culpability or any damage to anyone’s prickly self-esteem. Further, for many years now, people like those in Belmont have been told that they really haven’t earned what they have, that there really is no such thing as meritocracy, that they are simply “privileged,” that they just got lucky, won life’s lottery, and so on. Similarly, they have been told that people who are not doing well have done nothing wrong, but have been denied access and opportunity by an unjust society structured against them. The Belmonters may not really believe all this down deep, but that is the official line almost everyone is expected to take in public these days. (At one point, even prominent historian James McPherson defended racial preferences and attributed his own success to a kind of affirmative action that favored white males.) Then, too, since their success cannot be seen as the result of virtuous actions, but only of chance, Belmonters might fear that they can be deprived of it at any moment, when Lady Luck turns the other way.
Another reason could be that the Belmonters also want to be free to do what they want, or may want at some point to do (indulge in pot, pornography, adultery, gross popular culture, etc.), and don’t want to feel themselves judged in any way if and when they do.