I read an old blog post called
Eugenics doesn't work. Ask why, asshole. which I thought was well written and does a good job highlighting one of the problems with eugenics. There is the issue of selection pressure, culling individuals who are seen as "unfit" from a population only serves to make the population weaker and crueler.
A journal article is cited where the researchers were looking at artificial selection of chickens. Chickens, of course, have economic value so applying evolutionary theory in order to breed productive chickens is something people are interested in. What they did was look at what happens if they moved from picking the chickens that laid the most eggs in a multi-hen cage to looking at larger groups of chickens. Both the lifespan and egg production of the chickens improved dramatically. Instead of selecting for chickens that lay the most eggs, the farmers were originally selecting for the meanest chickens.
The author of the blog compares this to Enron. Enron was a company where they would measure productivity of employees and routinely fire the bottom 10-15% in an effort to recruit the most capable and most motivated people. This is a remarkably Darwinian selection process and, like with the chickens, Enron did not end up with the most productive employees, but the meanest. They retained people who drove down the productivity of other workers and cheated so they looked like they were better workers than they really were. We should all know what happened to Enron.
Eugenicists are the people who want to remove the bottom. If they have their way, they would repeat the same mistakes the farmers made with chickens and that Enron made with employees. It would not lead to a great society, it would fill one with sociopathic assholes. In many ways, this is the society we have crafted. We need to focus more on the group and less on individual performance and competition if we want to live well.