In a nutshell, I'm not here to teach economics classes:So no answer. I get it
the country cannot afford to continue spending the way it does.
The two main drivers of spending on the federal level are healthcare (Medicare and Medicaid) and Social Security.
The country already has a debt-to-GDP ratio of 120%, it is unsustainable. If the debt is not taken into a more controllable level soon (define soon however you want), buyers of our debt (investors, banks, and other countries) will eventually stop. Ths will cause yeilds to spike, bank runs, economic recessions, markets to fall, unemployment to rise etc..
Eventually the buyer of last resort will have to be the Federal Reserve.
This can/will lead to one of two scenarios:
1) Austerity.
2) Inflate our way out.