If you are asking /. you might not be convinced, or worse, not passionate about it.
What other thing you desire or better yet, you really need, can be attained with the same amount of money, time and sacrifice that you'd pour in a postdoc?
Most people do not realize there's better ways to invest in time, money and sacrifice.
Some need to pay for the education and be chased with deadlines to learn and/or get something done.
If you must go for formal education, I personally find more benefit in studying something new I don't have a remote clue about.