But how could I be marginalizing them if my argument stipulates that these groups (theists and capitalistic egotists) are in the majority? I'm assuming these groups are socially normal, and I'm asking how psychiatrists address the possibility of a crazy, harmful social norm.

I'm not dehumanizing anyone. I'm criticizing some social norms. Human nature includes the potential to be sane and insane, enlightened and deluded.