Eugenics was very common for intellectuals back in the day, until it was taken to the extreme and demoralized.
The basic premise is this. We help our poor stay alive. If you weren't helping the people in that Denny's video out with the basics they wouldn't be able to survive. So that's where darwinism and survival of the fittest fails because those people are NOT the fittest and if they were on their own they would die but we help them.
So in essence we are lowering the quality of humanity by helping those people who couldn't survive on their own. There are some people we'd rather have breeding than others. Do you not agree that you'd rather live next to Bill Gates kids than those people's kids? Would you rather have Mark Zuckerberg's wife pop out 12 kids than Latonda pop out 12 welfare babies? Do you not agree that Bill Gates kids have a better chance at advancing humanity than those animals who can't even take care of themselves?
Nobody is saying to KILL anybody already living, or not help people that are living, but there are certain people that are having more than their fair share of kids they can't take care of. Eugenics was very popular in the last century until the National Socialist workers party decided to start killing people deemed morally bankrupt off.
Do you want to take it to an extreme? Certainly not but what we're doing now is crazy too. We're paying people to have kids they can't take care of. China has already instituted population controls in the past, it would just be our form.