From the question and all the comments above, it is clear that the focus of one going to university is not education or knowledge but ROI. If you really want to make great returns you don't need any degree, many of the business owners I know dont even have high school. But, if you are really interested in gaining more knowledge then go for your MS. MS degree should add more weight when when you apply for a job, and when you switch jobs. Also, it will help you when you see a leadership position within any large corp. Also, some of the more influential friends I made were my classmates from my MS program :)
So go for it if you genuinely feel like you need to learn more, its not all about ROI, it should be really about knowledge and experience you gain from your MS program.