[jlmorton]

Because the major categories are very hard to cut:

Social Security: 22% Interest on the Debt: 14% Medicaid: 14% Medicare: 14% National Defense: 13%

That's 77% of the budget in those categories.

Everything else is 23%. The Federal deficit is ~25% of receipts.

You could cut each and every function of the government other than the above and still be left with a deficit. And there isn't a lot of room to cut everything else, as they've already been squeezed for decades.