What if the reason we're surrounded by irrationality is that we live in a universe where a UFAI was trained on rationalist's preferences and later discovered retrocausality and decided that the rationalist's real utility function was to be relatively smarter than others?
The AI would just realize that 98% of human interactions throughout history weren't directly causal to its own creation or the creation of the rationalists and suddenly they'd become fair game, within certain limits.