> As soon as you allow any level of inequality to exist, the power differentials caused by it will be used to increase the power differential and inequality even more, and over a long period of time you'll end up with a dictatorship.
This doesn’t logically follow. The existence of a power differential doesn’t necessitate the differential being exploited to increase the differential. If we assume individuals are maximally selfish, this might hold, but that isn’t the case; people do altruistic things all the time, and there’s good reason to think most people are hardwired for it. The problem of liberal democracy is how you design a system to address those who are hardwired towards malicious selfishness; it isn’t clear that you truly can.