This is a commonly known social phenomenon. High intelligent people gravitate towards subjects of policy and low intelligent people gravitate towards subjects of identity. High income social classes tend to contain a higher mix of high intelligent people than low income social classes.
EDIT
Ironically, as this comment receives down votes the comments rising to the top resolve to factors of identity.
It does not matter what your or my opinions say. What do the numbers say? We can be sad and hold hands about it, but that hardly seems like a solution to the problem.
I don't know how you could read this article and walk away with the conclusion you have. This is the actual conclusion:
Finally, the relationship between intelligence and political attitudes is most likely not fixed in some simple way, but probably changes across time and context.
You're being downvoted because your comment is rhetorical and blind to the fact that your policy-focused high income social classes are just non-traditional identities.
I am being down voted because it seems to make people sad. What do the measures say? This is something that has been researched to death in multiple countries multiple times through history. Feeling sad and ignoring the reality just means you are playing their game leveled against you.
In this case causation is irrelevant, because its clearly known. The goal is get the dollars, get the votes, with the causation being attitudes. Correlation is all that matters, because its how they modify attitudes to get what they want.
EDIT
Ironically, as this comment receives down votes the comments rising to the top resolve to factors of identity.