You see he is just average Joe. After 3 month or 6 month, he will claim he did call bottom or top correctly. It is marketing or book selling purpose.
The truth is market is always going like wave, up and down, it is pretty hard to find the bottom.
The general concept is any kind of guesses fails at some point of time, we need to keep up with market closely with high level economical outlook.
If someone ask, IS IT OVER NOW? No one can guarantee YES or NO except investor himself/herself.
Do not look at answer from web or blog, get the answer from your own methods.