Hear me out in this early bird thought of mine
You're an eugenicist, you only want the physically best amongst humans to survive (exceptions made for the fat, rotten, adrenochrome-guzzling billionaires that bankroll you and their more-inbred-than-the-House-of-Hapsburg-living-in-Alabama families of course)
So you make up a drug to kill and sterilize as much people as possible, and the mockingbird media and the jackboots will do their part to force as many as possible to take it.
Aaaaaand it's killing young, athletic and perfectly healthy individuals while the 400-lb neon-haired SJW's with a permanent double IV drip of Ben'n'Jerries and the malnourished vegan soyboys are still out there.
Makes even less of a sense if you're a white supremacist, in which case the shots should be completely decimating places like South America, South-East Asia, China and India.
What gives ?
I have speculated on this before. If you want to commit mass murder/genocide of a targeted population, you roll out a two-part chemical or biological weapon. Either half is not terribly deadly on its own, but the combination of the two are a solid kill. You roll out the first part and get everyone exposed to it. Some have adverse reactions, but overall it doesn't cause a significant awareness of your plans. The second roll out will be the specific people you plan to kill off. The people that you have not administered the second component will always be vulnerable to it and can ensure that you can eliminate any that do not follow your commands, thereafter. At least, that is how I would have planned it, if I was an evil devil-worshipping POS.