In part, killing capitalists is not killing capitalism. We need to make a society where people cannot wield that much power over others. Retribution is only a proxy to practical justice, not justice itself. The rich should be forced to give up their wealth, not punished for their actions. They should only be killed for resisting. Violence is necessary to deal with the violent, but it will never be inherently good.
This is the peak of evolution. It’s been downhill ever since.