The mistake the oligarchs will inevitably make every time is the destruction of the middle class in their voracious need to own and control all things. They never properly consider the middle class as their buffer against the anger of the poor and as the ranks of the poor grow they are left with no defenders except those who can be purchased outright within the government.

The enforcement of any “ism” is always rooted in violence or the threat of violence, so that should not be so quickly discounted as a means to counter it. Society condemns the violence of the individual who fights back but always approves of the systemic violence against him/her that strips them of any economic justice. Such systemic violence can only be maintained if a large enough group is able to overcome it, or never subjected to it in full, to achieve some satisfactory level of dignity that would cause them to democratically protect their perceived benefactors.

This will always split along racial lines as the first fired and last hired demographics are not considered fully “people” in stature and never look like the dominant oligarchs. These “others” will be convenient to do work for less than the dominant group will, and to serve as scapegoats for the resulting economic disruption that causes. People will also support a much higher level of militarism in their local government if they feel it is purposed for someone else that is easily defined as not themselves.

The greatest threat to the oligarchs isn’t extreme tax rates. It is being made irrelevant to the general economy. As long as the society remains structured around employment and industry they will remain perceived as “job creators” even though they have no ability to actually create any money in circulation. For that they must use their bankers to extend credit far past the ability of the economy to safely sustain, drawing resources forward in time to be monetized into profits that the government must backstop or risk the whole house of cards collapsing.