That chart can’t be right. Everyone knows that our Social Security we paid all these years is in a lock box.
Actually, it is a myth that the money for SS has been stolen. It has been effectively in a "lock box" gaining interest. The SS contributions are collected and put into non-market, interest-bearing T-bills. The SSTF is included in the $19 trillion national debt as a liability, just like the T-bills held by China or Japan.
SS is a pay as you go program. Today's workers pay for today's retirees. SS has been running in the red since 2010 (benefits paid out exceed revenue) and will continue to do so if left unreformed. As a result, the shortfall is made up by cashing in some T-bills from the SSTF by the General Fund. All of the T-bills will be exhausted by 2033. Thereafter, by law, SS benefits will reduced to only the level of revenue received--about a 20% reduction in benefits.
SS is going broke because it is actuarially unsound. Our aging population places more and more demands for benefits while the number of workers supporting the system declines. In 1950 there were 16 workers for every retiree; today it is less than 3; and by 2030 there will be two workers for every retiree. We will need to reduce benefits or increase taxes (as was done in 1983) or some combination thereof to keep the system solvent.