There will be another market crash, it’s not a big deal it happens every so often and life moves on.
If there is a war, the size and strength of the US Military virtually guarantees we will win.
It’s not so bad. Nothing can touch us.
Historically, the usual failure mode for empires that consistently inflate their currency is that those entrusted with the empire's military might become loyal to those who can pay them with hard assets that don't lose value as soon as they receive them, whether it be foreign currency, Bitcoin, land, or private data that they don't want to become public. Basically, you get warlords and mercenaries, and society reverts to a quasi-feudal system. The risk isn't war in the sense of Great-Power conflicts, it's war in the sense of national disintegration, like what happened in Russia, Venezuela, Yugoslavia, Zaire, Somalia, and Rome.
Some amount of debt is okay and takes this into account. But we are overdoing it.
Ironically, we could "fix" most our debt by allowing in a larger flow of immigrants. You-know-who would do you-know-what in their pants over such an idea.