Entrepreneurs fail for lots of reasons. Most entrepreneurs fail, by the way, so lists that describe why they fail should be helpful if only as mirrors entrepreneurs can hold up to their faces.
Not Smart Enough
It does not mean that you need to be highly educated or you are required with high level IQ. Some people just do not understand that where is something going wrong. They do not understand their field which leads to failure.
Not Knowing Who Is Who?
Separating friends from enemies is a difficult task. Usually people can not understand the difference which makes them fool and a great cause of loss in many ways. You should not trust blindly every one.
There are also many reasons of failure which involves:
Not finding enough funds
High expectations and less work
Horrible soft skills