Because we have no idea how any of this works, selecting against one gene may have negative externalities that we don't even know how to measure. For example: a genetic cure for schizophrenia also dulling the creative traits it's correlated with. We cant even really understand how an emergent property like language works (see: every conlang), and you think we can engineer a civilization to be better by radically altering the balance of potential equality that we have been genetically optimized for?
A society of 120 IQ adults would probably be an insufferable hell beyond comprehension, considering the track record of intellectual movements and the proclivity of smart individuals, probably like yourself, to vastly overestimate the merits of rationality and concepts that can be limited to the mind of one human.
A society of 120 IQ adults would probably be an insufferable hell beyond comprehension, considering the track record of intellectual movements and the proclivity of smart individuals, probably like yourself, to vastly overestimate the merits of rationality and concepts that can be limited to the mind of one human.