You eventually run out of people. People to work in your factories and to consume the products those factories make. If you don’t pay a wage people can live on and the people who are working can’t consume things then you don’t really have an economy except for the military/security apparatus that’s required to keep people from revolting. The end result of unchecked wealth and power is an autocracy and those end up failing economically in comparison to democracies. I like the analogy of a black hole. At a certain point too much power is concentrated in the middle and the whole system collapses in on itself instead of shining brightly as a star.