I believe the world never really recovered from the 2008 financial crisis.
I think that is when we needed to do two things in the USA:
1. Raise interest rates and force people and companies to be more responsible with spending decisions.
2. Recognize the danger in any company becoming "too big to fail" and making sure that could no longer happen.
We didn't do either. Bad fiscal decisions kept being made because borrowing was so easy. Corporations have continued to grow larger and swallow up any attempts at competition, thus creating massive mega-companies that can harm the economy if they are mismanaged.
Those aren't the only mistakes being made, but they create the environment in which an economic downturn has the capacity to become much worse and much more difficult to deal with.