The smart few vs the dumb many, you're not going to convince 80% of people to let you sterilize them or prevent them from breeding. You'll have to either lie to them and sterilize them covertly, then deal with the Children of Men-style global warfare that results, or you'll have to forcibly mass-depopulate them, and deal with the global warfare that results. You will never get the masses on the side of depopulating themselves because they're undesirable, and you'll never get a majority of the truly smart people to consent to mass depopulation of undesirables, because of their moral hangups. Any group or system that tries to depopulate the masses and create Mein Superior Race will be regarded as evil and destroyed, because regardless of how correct they are and how beneficial to humanity their plan is, the masses operate on self-preservation and will destroy those who threaten their individual survival and procreation directives. It is a plan that cannot succeed because the very nature of humanity prevents it from happening.