It's only a hypothesis and all cognitive impairment is not uniform.

You might prefer the term "conspiracy theory"

Who cares about taxes when you can print money?

Money has value because of what it buys.

If a society is making 400 widgets it doesn't matter whether each is priced at $2 or $999, the government will only be able to get 400 widgets.

A stupider population makes much less widgets.

What if a country's economy doesn't make widgets at all but merely controls the system of international finance which is premised upon its own debt?

Do the people at the top care if the population can make 400 widgets, or that they maintain their status?

> strongly associated with dissatisfaction and violence,

dissatisfaction and violence are the easiest problems for a state to deal with.