Also, look up the genesis of the conservative media apparatus - specifically, Roger Ailes, Rupert Murdoch, and how that whole thing came to be in the post-Nixon era. There’s a lot of context, and none of it was done in good faith. The intent was always to game social norms and leverage populist appeals to emotion into tribal ideologies (I.e. us-vs-them/ingroup-vs-outgroup). That’s ultimately the fundamental basis for conservatism.
These days, foreign influence operations (often based in authoritarian countries) aimed at increasing the polarization of a target population also play a major role.