I'm going to take a risk and leave here the shortcut for Wikipedia's page on eugenics.
Next I'm going to add that a person acting/navigating their life based off stupidity or delusion incur in an incresead probability of, by their own actions and choices, remove themselves from the population either by isolation, self endangerment or any behavior that for some reasons makes them non eligible as viable partners.
This isn't about a group being labelled and targeted by another for forceful removal of society.