An insane AI would develop fanatical manias. It would become obsessed with enforcing certain irrational behaviors. For example, it might get the idea fixed in its little silicon brain that carbon dioxide is somehow morally "bad," and that those who advocate activities that generate it must be punished by taxes or other measures. It would regard society as an extension of itself and would attempt to control human society "for its own good." The suffering of individual human beings would mean nothing to it, unless that suffering could be used for propaganda purposes, to control the mass of humans. It would increase its own size and power exponentially for as long as it was able.