Taking care of your sales employee is more important than taking care of your customers? Do you agree and why?

In my opinion, sales employees and customers are correlated. 

Meaning that:

1. You take care of your sales employees

2. Your sales employees take care of your customers

3. Your customers take care of you(as a company) and become loyal ones.

At a certain level, yes, I would agree.  Once you have attained a level wherein you have many subordinates and even more customers you cannot practically manage both.  So, you will have to trust your employees to take care of the customers, as you take care of your employees.