Sunko - a derogatory term for someone who holds strong beliefs in something despite overwhelming evidence to the contrary. One who is subject to the sunk cost fallacy fallacy.
Example: These sunko boomers still think trickle-down economics are legit. Jokes on them, the only thing trickling down will be their piss down their own legs when the underfunded state nursing home caretakers ignore them for 3 days straight after we refuse to subsidise their geriatricity.