Point to the part in any definition of eugenics where it says that.
Clubs like Mensa were created as an eugenicist exercise to get high-IQ individuals to breed. There is no force, there is no punishment for not being in them, there are only individual choices.
It's still an attempt to alter the human gene pool through selective breeding, positive or negative, personal or systemic.
Saying "I don't want kids" isn't eugenics.
Saying "I don't want to risk passing down my depression" is.
So is "I want to have kids with this person so our children will have trait X"
