Yes... except it is a legal ponzi scheme.
Everyone knows that it is a ponzi scheme. At some point in the future, whether 100 or 1,000 or 10,000 years, some are not going to get their money back. The assumption is that it won't matter because none of us will exist any longer and won't need it. But, that is the reality of why everyone can't take their cut and invest it now. If everyone asks for their money now, to create their own portfolio, it would crumble. That is how all ponzi schemes crumble.
It is also why sustainable population growth is necessary and why many countries are begging people to immigrate there. If our population starts to decline, we have major problems. Have babies or else encourage practical immigration if you want your full social security and Medicare benefits.