FDR said what he thought the purpose was. I believe him.
Currently it is an inter-generational, that's why it will fail. So you're saying that we should allow it to fail rather than fix it?
If we can provide for retirees without screwing current workers, wouldn't that be better?
It MUST be inter-generational by the law of physics. The money and system of ownership are the artificial constructs designed to facilitate exchange of goods. But they become a virtual reality confusing and hypnotising to the believers in the free market.
Make such mental experiment - imagine that all people decide not to have children and instead to invest saved resources in economy. Such generation will be VERY succesful until it becomes old. Then suddenly for "mysterious" reason the horrible crash will occur. All investments and savings will disapear and there will be plenty of old starving people dying like flies and begging foreigners to come and take over.