> If things work so well that everyone's quality or life is improved, why would there be dissent large enough to worry about.

Have you met people?

Sure. There's always going to be someone opposing something. But I'm not aware of cases where a disagreement in an environment good for everyone was large enough that it caused the leadership/government collapse. Similarly on a small scale, the number of grumpy people at companies I worked at scaled more or less with how good things were for everyone.

In other words, if things are good enough, there will be more people disagreeing with the totalitarian part than with the overall conditions.

Foreign state-actors love to sow discontent in enemy territories. It doesn't matter what they say to rile up the population and cause instability -- they'll just do it.