Why the Boom Makes the Bust Inevitable

The boom, bust cycle. .. this is something that is very rarely understood in its proper form. Many people call it the business cycle, some people call it the debt cycle. So, what we're going to look into today is, What causes the boom bust cycle? Why does the boom make the bust inevitable? If the bust is inevitable? Why are there historic examples where it seems as though there was no bust when there should've been one.