Fiat money is a bubble but the probability of bursting and bubble bursting rate is very low. Money FIAT is a unit representing the economy of a country. The country's economic sectors and the type of assets it owns are guaranteed for the currency they issue. It could be called that. If the economy develops stably, the political situation is stable and they have good monetary management measures, the bubble market will not break.
But that is precisely the issue, you are believing their lie that somehow it is possible to have money that is not backed by anything and that they can print at will and that they do not have to communicate to their citizens how much of it are they printing and that somehow this is not going to affect the economy of the country, all governments around the world believe their own lie and think that they have perfected the way to keep printing money forever and getting away with.
Only to discover too late that what they believe was a lie and that they cannot keep violating basic economic principles and keep printing as much money as they want, it is not possible, at some point the bubble will have to burst.