I'm somewhat confused. Do you think money wouldn't exist in another economic system? Currency isn't an economic system, and humanity has almost always used a currency to exchange goods. During feudalism, landlords used land as a form of currency.

Billionaires indirectly pass laws through lobbying and financing campaigns. In 2010, the Citizen's United case allowed them to fund an unlimited amount, and our government caters to the small minority. Some of our politicians were board members for banks, oil and gas, agriculture, and other businesses. Billionaires and government intermix, and in the UK it's called a shadow government.