I don't see how they are fungible. At the end of the day the people are investors. They invest in a real company that carries out real business. Is that business any of those listed above? If not, then yes you can invest, if not no you can not invest. Obviously the investors would at some point see a return on their income. And you simply don't give them the returns. You put the returns back in the same fund. You can get that money back when you are 65 to pass to your children. You can only get back a certain amount, depending on the number of children, enough to pay for their schooling and a home. That way everyone has an education and a home, and the banksters don't get rich off mortgages and loans. The residual the government can keep for social programs or something as such.