It's basically about racism and control. One of the key reasons the US didn't get universal healthcare in the Social Security Act of 1935(!) was because FDR relied on Southern Democrats who thought it was a threat to segregation. That culture is still very much alive.
Conservatives in the US see the world as a power hierarchy and their most important job is to uphold it, like they are princes next in line to be King. See how hard they fight China and cut social services to funnel money up to billionaires. They will literally die for it.
Their inheritable privilege dies forever if they don’t fight to uphold it, and the one rule of all landed gentry is never to jeopardize the family’s privileges, under penalty of disinheritance and expulsion.
Yeah. This tribal territorial zero-sum perspective is the original form of politics. It doesn't work so well in a modern knowledge-based multicultural world, but the DNA hasn't caught up yet.