A lot of factors could make a business fail. I'd like to just add an extra reason for business failure.
Lack of commitment and dedication to the business: There's no way your business would grow if you don't stay committed to it. There are no two ways about it. Lack of commitment would make you not notice areas that are failing and slowly it eats up the system and finally crashes the business. Learn to devote time for your business.
Thanks for the contribution @tomlee, without dedication and commitment in a business, there is definitely no way for growth.