How many times do we have to repeat this until someone listens?

Unsustainable means not sustainable; not to be supported, maintained, upheld, or corroborated.

...taxpayers are on the hook for Social Security and Medicare by these amounts: Social Security, 1.3% of GDP; Medicare part A, 2.8% of GDP; Medicare part B, 2.8% of GDP; and Medicare part D, 1.2% of GDP. This adds up to 8.1% of GDP. Thus federal income taxes for every taxpayer would have to rise by roughly 81% to pay all of the benefits promised by these programs under current law over and above the payroll tax.

Unless of course you think that our economy can sustain an 81% federal tax increase.