Billionaires there are subjects to the regime, and only remain billionaires while they are absolutely loyal to the regime. And threat of disagreement not only would cause them stop being billionaires, but also stop breathing altogether. I mean, running away could be an option, but then one stops being Russian or Chinese billionaire. And also this may not preclude "stop breathing" option, as some examples show.
You're right! Still they are billionaires in their countries with many benefits for being billionaires! Except, steering the government where they want - which typically means getting even richer. In the USA this happened, though.
My point is that, even in self-proclamed democracies, it's quite hard to actually give power to the people, precisely as in regimes. It's not a "it's all the same" position, of course: I mean to say that taking some values as absolute is not great if we don't clearly define what we are optimizing for. The USA model of democracy doesn't optimize for individual freedom nor for general population happiness.
