"When, for instance, competition laws are not enforced, monopolies grow, and with them the income of monopolists. Competition, by contrast, drives profits down." - "Some Are More Unequal Than Others", Joseph E. Stiglitz, New York Times 2012-10-26
The article relates how the oligopolists are over and over driving down their costs, including taxes and wages, and increasing their profits.
My thought is that there may be a time when there are no profits to made because few can afford to buy the oligopolists' products and services and there will be insufficient qualified employees because there were insufficient taxes to educate a large number of people.
See "fastest to ruin" quote in "The Invisible Adam Smith".