Customers and users are not the same thing. The distinction is important but often missed.
A user is someone who uses the software you make.
A customer is someone who chooses to give you money for your software.
For many classes of software (eg a POS system), the majority of legitimate software users are not customers. They are using software chosen by someone else, often their employer, or an OEM.
The first step to satisfying both users and customers is to not confuse them.