Menial work et al. will be done by bots, and STEM is a field that is not only limited by training (they have been de-skilling Western workforces since the 90s); but, by innate skill as well (see: why the Third World is the Third World)... So, they need to dilute the ranks of humans (Caucasians and East Asians), so that they do not spoil and revolt once they are given the ultimatum of either "UBI" penurity + a V. R. headset, or euthanasia.