This problem could be solved with robots as well. Why not having farming robots alongside with ones which protect them and the products of their labor from the greedy hands of the have-nots? It could be that robots able to kill will overturn the balance to the ones who can afford them even if they are a few. Who would dare to stop them?
If you have nothing to lose as a have-not, your options for action are extensive.
Even the smallest nation-states can afford and manufacture nuclear weapons now (ie North Korea). I don't foresee this capability getting more expensive or more difficult as time goes on, only cheaper and easier.