No degree will guarantee you a job. Professional degrees (law, engn, accounting, medicine etc) will come close, if you want to work in a profession.
Every other course will just give you a better chance of getting a job, and help you perform better once you get there. A math grad can solve all kinds of problems that other people will just shrug their shoulders at. That's always useful.
Academia in general is a dangerous career path though. Too many people on the ground floor (i.e. every undergrad who can't think of a better thing than grad school), too much glamor keeping them there, very bureaucratic organizations, and a complete mismatch between work (research) and funding (students).
Every other course will just give you a better chance of getting a job, and help you perform better once you get there. A math grad can solve all kinds of problems that other people will just shrug their shoulders at. That's always useful.
Academia in general is a dangerous career path though. Too many people on the ground floor (i.e. every undergrad who can't think of a better thing than grad school), too much glamor keeping them there, very bureaucratic organizations, and a complete mismatch between work (research) and funding (students).