Your statement of fact is an assumption, probably based on longer life. I have read no study that shows more is taken out then was put in by individuals.
What you fail to see is that many elderly do not take from social security at all, even though they can. Many people never reach old age; just consider all the wars and all the dead young people who paid into but never reached old age.
So, although I agree with you that, under the system as it turned out, it is taking from one person to give to another. But big D is also right, it isn't the fault of the person who paid into such a scheme that the money is gone, forcing others to pay the bill.