The united states live from their good reputation.
Although they have already been nearly insolvent a few times during the last years, the USA get negative real interest rates on government debt.
That means the market believes that there are no alternatives with sufficiently low risk.
Hopefully the market is not wrong.
The US credability will be lost soon and the US dollar will crash.
Will bitcoin also crash if dollar crash? most of bitcoin buying through fiat is done with dollar,if it crashes,there will be less buying
No. When the buying power of dollars is getting crashed out, interestingly bitcoin will get more power in term of buying capability. Usually dollar and gold are inverted connected so we can assume bitcoin too. When dollar will lose its value, bitcoin will gain.
Buying bitcoins using fiats has nothing to do with this by any means. (If dollar crashed out, we just need more dollars to buy one bitcoin.)