This time is not different in the sense that at some point crazy valuations get a reality check. But that's not "the crash of the US economy", that's a stock market crash, and those will happen (tell me when - I'd also like to know) and they also tend to crash all around the world.

The US economy has had ups and downs and I'm sure will still have but despite the wishful thinking of Marxists it's still the least worst economy around in perhaps the least worst country. It still attracts talent and money. It still leads in many areas. It's still very productive. There are huge ecosystems and a cultural base. It's still the world's largest economy. Where will the balance tilt? China? India?

Anyways, be careful of what you wish for, if the power shifts to China we are going to have a very different world, and not in a good way. I don't think it's even in China's interest to see a large decline of the US, after all they're a big customer.