"invested" money is going to pay returns on previous "investments", like your dad. It would be illegal and people would be going to jail, if it wasn't the gov't doing it.
Let's call it what it is, a tax to support lower income senior citizens. Then get rid of the whole retirement investment language when referring to it and have an honest conversation about the future of it and retirement funding in this country.
I don't plan to see a penny of SS when I retire.