When people talk about existential risk fears, this is without a doubt my fear. All it would take is a small group that is ethnically supremacist and technically capable. How many edge-lords joke that the problem with the world is that there are too many people? Imagine you could drastically reduce overall population while maintaining your own ethnicity. And it could be done slowly, a harsh flu now and again that affects the general population at a much higher percentage while sparing your own kin. It's terrifying to think this could be justified in the minds of some.
Though that's a chilling thought, I am more worried about someone trying to produce such a bioweapon, but just doing an amateur job and killing us all with their buggy alpha release.
https://en.wikipedia.org/wiki/Gene_drive