Answer:
First, you need customers who are interested in your product. Since most people don't go to banks anymore (anybody remember when banks would help you balance your checking, help you directly without showing you either a house phone or computer to a call center?), it is a difficult job to sell. Phone calls don't always work because so many fraudulent transactions have resulted. Same with letters. Your sales skills only get you so far. A family member found the job almost impossible due to the quotas for cross-selling, tracking and lack of products that also made sense for the customers.