Can our country America/USA really "go under/down" per the economy-national debt and what would that be like?

I am very concerned about our economic problems and national debt. Obama has seemed like an anti president in that he has seemed hell bent on destroying us economically. Could we really collapse economically? Isn't this just scare tactics? Can't the politicians simply tweak some things, when things get really bleak, to fix the problems. We have a cultural tendency not to react until late in the game but we always seem to pull thru. What would economic collapse look like per my daily life? I mean there would still be grocery stores, parks, apartments, jobs, etc. It is not as if we would be living as cave people in a post apocolyptic world.