A master's in a science or most scholarly fields is just a signal that you crashed out of a Ph.D. program - it's better not to admit to having one.[1] But you remind me that I left out another reason you might want to pay for graduate school: to get an MBA or other specialized business-type degree (international finance, accounting, etc.), that can be a good strategic move for some people - and can actually be rewarding and interesting if you get it at a good institution.

[1] Some Ph.D. programs routinely award Master's on the way to the doctorate; I'm talking about terminal Master's.