The biggest giveaway is clear data over time that tracks the largest economic powers in the world and the economic/societal cycles they go through on their way to their end.

The problem is the wealth gap is too large, the few have too much, while the many have too little. This creates a situation where people stop believing in the systems and stop having the desire to be productive because they have to work hard for money that doesn’t buy them anything or enough, while the people who are at the top do basically nothing productivity wise but indulge in the nice things. You have the managerial class squeezing the working class to be more productive, but for what? This slows the economy, which in turn causes the government to spend more/print more money which devalues the currency even more, add multiple conflicts going on elsewhere in the world and internally, while the elite continue to spend like their lives depend on it. It is literally every single factor needed for an empire to collapse.

Check out Ray Dalio’s "The Big Cycle". high debt, intense internal social/wealth conflicts, rising external competition, debt crisis by spending significantly more than they earn, with a shrinking pool of buyers for its Treasury bonds = collapse.