why is MBA so popular

There sure is a degree for Master of Finance (MFin). Some schools may offer it as Master of Science in Finance (MSF).They will be suitable for those with careers in the financial fields - broker, banker, etc. A more comprehensive track will be an MBA with specialization in Finance. Then besides finance related courses, one would also learn about management, marketing, operations and other aspects of managing a business. Which may come in handy if one wants to do something in a different field.

I guess MBA is popular because all businessed need some management. Also, a college graduate with any degree, be it engineering, music, or chemistry, can move on to get an MBA degree. However for most other Master degrees, you need to have a related undergraduate degree first. Moreover, with some degrees, if you move on to the a master, it would narrow down your career path to being a professor or researcher, but an MBA degree actually boardens your career choice to move into the management level, where supposedly the earning potential is better.