For example, if you check your history books, looking at the 1930's depression. Well, that followed a post war boom. So, the 1920'swas a boom time, but that caused financial excess, and therefore, the 1930's, depression.
The bubble was caused by us, by people buying property, taking on debt. So, it's quite clear that preceding these crises that we have seen over the last 100 years or so have been periods of mania, and greed, and instability. And that's how to understand the causes of financial crisis. .