This might sound like a naive question, but I mean it quite honestly (please be aware that I am merely a high school student): Why does the United States' government debt matter? To be sure, based on political affiliation there are different degrees of opinion as to how urgent the problem is, but few seem to contest that the ballooning national debt is at least somewhat a concern.
I must confess, I don't quite get it. Given that the United States is so powerful, can't the government just keep borrowing from other countries? (And then just pay off the debt to Country A with more borrowing from Country B, etc., etc.?) Why can't the United States do that forever? Is there really a legitimate danger that other countries will get scared to lend us money (I'm assuming that's the concern about large debt)?
I know other people have asked questions about government debt on this site before, but I haven't been able to find an answer that squarely addresses my present concern, so I thought I'd share this question with you all. Any help is greatly appreciated.