Why aren’t you earning more money at this stage of your career?

You would like to earn more, however other aspect are more important.

Example:

“Making money is important, and that is why I am here. Throughout my work history what I have always considered more important is to do work that I like and am good at, with a company I like and respect.”

(Be ready with specifics on your perfect position and company, matching them to the position offered.)