If you want a “real” answer, it’s that the small number of people left on earth at that point would quickly split into groups and start warring with each other over resources since all infrastructure would probably shut down with no one left to do menial day to say jobs anymore. If not that then the people with 180 IQs would start planning to sterilize half the remaining population and that would start a war. The fundamental flaw in your hypothesis is assuming that these so called “smart” people would also have common sense, empathy, or just common decency but since they’re all super cool with forced sterilization then they probably have none of these