It is not only income inequality one needs to look at, it is the amount of the baseline population which is well fed and taken care of, as generally, those that are will not wage war against the rich, while those that aren't are much more likely to.

If 90% of the population is starving and makes 10 dollars a day (hypothetical numbers), and 10% are rich and make 100 a day, the poor will be much more likely to revolt than in a scenario where 90% make 100 a day and can afford food, shelter, education etc, and the 10% make 1 million per day. It is not the level of inequality, it's the baseline.