Read what MMT has to say about what money is and how it works. I agree with over 95% of what MMT has to say about what money is (in our post gold-standard world). Here's a really good working paper on the subject:
http://www.levyinstitute.org/pubs/wp_658.pdf The best place to start in my opinion.
One of these days.... 100 years.... 500 years.... when fiat money has been the norm long enough, citizens and governments will understand it well enough to ditch the broken thinking that comes from forcing our fiscal and monetary policies to conform to the rules when hard-money was in effect.
In short, sovereign governments that issue their own currency are not bound by the same fiscal restraints as individuals, households, or even state governments. Sovereign (currency-issuing) governments don't borrow money, they create money. The "national debt" is a misnomer. It is not a really a debt at all. It is just a number representing the total financial assets created by the government to serve the public's need for currency. Note: While it is true that interest is paid by the government on treasuries, that is NOT a requirement. This is a way for the government to encourage saving/investing by determining the rate it pays on savings, not a method for borrowing money.
If you believe that the US or any other government (that issues currency) should a) balance it's budget and/or b) pay down it's "national debt" you should ask yourself why.
If you believe the government really "borrows" money instead of creating it, ask yourself.... from whom does it borrow the money? After all, who else can make US dollars for the government to "borrow" in the first place.
There are still some hard-money advocates out there, who believe that we should return to the days of hard-money where sovereign governments should "borrow" money from those who already have it instead of creating it. Those folks propose pegging the value of money to gold or some other physical substance, as it was before 1971ish. Whether you believe that or not, MMT does a great job of explaining how money really works since governments around the world did abandon the gold standard.
as arebelspy correctly points out: The potential threat in a fiat money system is inflation. But for a serious student of the alternative (and I know of no other besides some hard-money standard like gold), that risk is not so scary when the inadequacies of that system are understood. Inherent unfairness, and the very real risk of deflation being the two most common.
Where real-world planning is concerned. Owning marketable skills and hard assets like real estate are the best hedge against inflation.
Happy reading! It's exciting stuff!