Patterns:

There are patterns in history. But patterns can be broken. The great depression was mostly cause by central banks, the Federal Reserve, etc, in the 1920's, in America. Now, that kind of thing affected the world.

Centralization

One of the biggest problems is when people rely too much on the dollar or other centralized fiat currencies, etc.

Bubble

Right now, the majority of the world is stuck in an economic bubble that can pop.

Prepare

That is why people must buy gold, silver, cryptocurrencies, land, canned foods, water filters, solar panels, etc, before it is too late. Because the economy can go down at any second in many countries around the world. Better safe than sorry.