Well, it depends on what you're going for. Some people like me are just fascinated by a particular subject area and just want the experience. I have a master of music composition. Can I do anything with it? No. But I have the satisfaction of knowing that MY work stands approved by experts who are active in the field; and most importantly those particular experts are composers and theorists who I admire as much for strength of character as regular people as I do their commitment to artistic integrity and high academic standards. That meant a lot to me and I just hope that the work I do, whether I'm commissioned or paid for my work, honors the composers who gave me my degree.
Now, reality is that you can't make money with a master's degree in music composition. Sure, it opened a few doors for me and earned me a higher starting salary when I taught school. But I don't get paid to compose music. I teach piano lessons and, well, pretty much whatever musical instrument people want since I used to be a credentialed band director before I started teaching privately. I've maintained credentials, I just haven't applied for a new teaching license since my last one lapsed. I'm not certified by any music teacher unions or anything because, well, nobody cares and it doesn't make much difference. I also play in bands every chance I get, I play for fundraisers, private parties, and even have a part-time salaried church gig--and those are extremely hard to find for instrumentalists. I have an eclectic range of musical abilities and interests, which is how I've survived and contributed to my family's finances. I'm fortunate in that while I don't bring in much money, I have plenty of time to pursue music composition on my own and will actually have a handbell duet performance with an orchestra tomorrow night! No, I'm not getting paid for it--but the honor of getting to perform an original composition with an orchestra is payment enough for me.
I think master's degrees are really more for people who are seeking leadership roles within their respective real-world communities, not merely academic accomplishment. I have a cousin who earned her MBA and had to face the harsh reality that nobody is HIRING MBAs in her geographic area. So she got in nursing school at the nearest community college and actually flunked out of that program. The minute I heard she was enrolling in the nursing program I instantly thought it was a bad idea. The whole time I was just wondering with the experience she got getting her MBA, why couldn't she just research the needs of her area, borrow a little overhead money from a bank, and start her own business? Nothing against nurses, but you go from a MBA program to cleaning up human blood, snot, and poo--I mean, being pampered and spoiled for 5.5 academic years is not going to leave you well-suited for a job that is beneath you relative to that kind of background. I believe in pressing forward, not wasting your academic life by starting completely over.
You want a REAL job with a master's degree? Let's say you have an MBA. First, research your geographical area in which you want to work. Find a small business that's obviously failing. Make friends with the owner. Buy him out or offer to work for free as a "consultant." You know, as "research." If you manage to turn things completely around, sell the business to someone genuinely interested in it or at the very least get a solid letter of recommendation from the business owner (if you don't own it). Pad your CV with those kinds of work experiences and you can show the kinds of firms you want to work for (if you don't start your own) that you are a self-starter and have marketable skills.
Or if you have a M.Mus. like me, write orchestra music, learn how to play other instruments than your major instrument/voice, network with local musicians, partner with local arts councils, volunteer as a board member on the local symphony association if you have one, run for executive offices in arts organizations, regularly attend local school board meetings, go to town hall meetings, etc. etc. Take advantage of every opportunity to do something creative that you can share with your community. Hold a community talent show in which your band is the featured exhibition band. Promote yourself on Youtube, facebook, twitter, etc. Donate as much money as you can afford to your community theater so your name will appear on the program, volunteer in the pit orchestra if they do musicals, write and perform incidental music for non-musical plays... Volunteer to play every Sunday at church, organize church musicians, put together your own choir apart from the regular church choir...
Otherwise, all a master's degree will be is a worthless piece of paper. If you know what you're doing, get out there and make something of yourself. Don't depend on a piece of paper to open every door. That's not how it works.