As I see it, a PhD is for someone who is really passionate about the field, someone who wants to push the boundaries of our understanding of the field. PhDs don't enjoy monetary profit that is relative to the hard work of obtaining a PhD, at least that is my opinion. Though there are some good jobs for PhDs out in the private sector, the best place seems to be either in an academic environment, or in venture startup with close academic associations.
If you absolutely Love learning about the field, want to gain an understanding in a highly specialized knowledge set in the field of choice, want to be a part of cutting edge research that may open new avenues of understanding in the field, and don't mind working long hours, having little job security, having little reward, constantly being plagued by insufficient funding, repeatedly facing rejections and failures after months of invested work, and receiving little or no recognition for successes, Then a PhD might be a good option for you.
If you want wealth, job security, versatility, and set working hours, then a masters degree would be a better option for graduate studies.