The time, effort, and money would be better spent improving your pilot skills and resume.

Not taking a 'better' job because it would interfere with your masters degree might be the biggest mistake. If you want to be a professional pilot focus on that.

A masters degree might help slightly. A weaker resume, to get a masters, doesn't.

A masters helps if you medical out.

Now in x years, if you're a young CKA, cranking out hours, mentoring others, working in the union or flight department, and have the extra brain power to go out and get a masters? Rock on!

As an add on it's a slight positive. When it reduces other areas of your resume the value might become questionable.