1) [Economic] conservatives generally consider poor people an out-group (often even when accountancy would consider said person poor) 2) Said conservatives are almost universally white 3) Everybody on Earth considers people of other races an out-group 4) Everyone on Earth wishes to help their in-group before their out-group, if they wish to help out-groups at all 5) In the USA, poverty is highly correlated with being black and/or Hispanic, for a variety of reasons, including failure to choose the proper parents

7) Well off White Liberals consider Poor Whites an out-group. They do not consider well off Blacks an out-group.

(the "why do poor white folks often favor upwards redistribution?" problem).

Poor working class White Males don't really have much to gain from the modern mainstream left. They don't have much to gain from the modern mainstream right either to be honest, but the left is blatantly enough hostile to them that its easier to figure out. It is easy to dislike those who look down on you. It is much harder to see through displays of religion and false patriotism.