Robots are not as efficient as you might think, because the sourcing of materials, production, and maintenance of robots is not able to be entirely automated. Considerable development will be required to enable a completely automated industrial loop, and that will require a substantial and willing labor market. A few nukes will utterly remove the willingness of that labor market, even if it does not eliminate the laborers completely.

Money is not wealth. Wealth is what you can buy with money, and that depends on people being willing to exchange wealth for money, which they are less and less as money is more and more simply conjured out of thin air. The more reduced in actual wealth individuals are, the less they are willing to exchange what wealth they have for money.

Power remains dependent on population, and will for the foreseeable future, so the vampires remain dependent on population size today, and will until automated industrial production becomes a closed loop independent of labor.