Reply #5: Their goal is to get away with it

[gratuitous]

When the Republicans bumped the withholding in 1983 to create the surplus, they immediately started plundering it. Every now and then, someone notices that all that "spoken for" money isn't really there (through financial legerdemain and not a few shenanigans, it's invested in government bonds and other securities), and "deficit reduction" becomes a talking point. This usually happens when a Democrat is in the White House.

There are two ways to remedy the situation: Make those who took the money put it back, or pretend that the trust fund is a drain on the budget. Putting the money back would cost the Republicans and their fatcat welfare queen benefactors some of their ill-gotten goods. So they work overtime to pretend that the social security beneficiaries are really the reason for the "drain" on the Treasury. Don't pay out any benefits, or delay paying benefits, and voila! Nobody has to pay back the money Republicans "borrowed" to finance tax cuts for themselves and their wealthy pals.