No
Do a Finance Ph.D if you can becasue:
(1) it is free (full financial support plus $28K stipend)
(2) you are Doctor xxxx.
(3) you can get an MBA along the way easily if you want.
(4) more opportunities. You can be a professor in B-school which is at least $100k starting salary now

(5) MBA is rediculously seasonal. If you are lucky when you graduate, you get a good deal with possible tuition reimbursement. Otherwise, you can not even find a job becasue there is no ROCK-SOLID skills behind MBA.
I agree with the my_gc_2000. The best investment is to invest yourself. Unfortunately, education investment should be aligned with your expectation.
I get a Master in Statistics from a top 10 program, then another master in Computer Science from a top 10 program also (part time, company pays it). I found there are some overlap between this two. However, formal education in cs is very helpful too even though it will not double my salary.
I wish I can do a Ph.D in finance. Unfortunately, i am 30 years old now and there is a family to support
Ph.D is not directly linked to your intelligence, but sometimes the title is useful. For a master, you have to prove hard that you are smart. It is relatively easier for someone to trust a Ph.D than to trust a master. This is the social trend. So if you are young and there is no severe financial burden, then get a Ph.D.