When run unchecked, capital will happily suck all the money from the economy and into its coffers, and the fun thing is, it has no idea what to do next. Next it would very likely invest these money in the worst possible way and cause a big crash. Think about is like of a centipede instead of sentient creatures at work. It does not know what to do once it eats its leaf. We know it's going to morph but the thing is oblivious to it itself.