You don't get it do you?
Just as alchemy led to chemistry, and astrology led to astronomy, eugenics led to genetics. The poor saps marching in Yorktown are no different than the modern day believers of horoscopes or searchers of the philosopher's stone. The movement has advanced and moved on, they didn't.
The Nazis' attempt at purification (genocide) and selective breeding was about as effective as using Jean Dixon to explore Mars. The goal today isn't to improve the species by selective breeding, it's to create a new species in the lab....in vitro. Of course it won't include me or mine, but neither will colonies around Alpha Centauri. Doesn't mean it's not a worthwhile goal.
Why feel the need to kill off the competition when they cease being competition?