If it's money that an individual would otherwise have to borrow, meaning they'd take out a loan against a credit card or run up a balance, they are better off economically if they borrow from themselves.
So there is a bookkeeping way to say that I am not using the Social Security cash flow, but the overall effect on the taxpayer and the economy is the same. The government is borrowing additional net money.
We are urged each and every day to spend and borrow and live for the moment. Don't you know that you can't live without that 51-inch projection television? How can you conceivably drive a 15-year-old car?