Earning a PhD is a costly endeavor, but not usually directly to the student.  Many PhD and other advanced degree programs are generously appointed by scholarships and grants from organizations, government institutions, and benefactors.  The financial cost of that doctoral degree you’ve been thinking about for years would most likely be covered by society, which benefits greatly from the presence of highly educated individuals who have completely mastered a subject or topic and can provide services to humanity that others are less capable of.  The cost to the student usually comes in the form of time devoted to living the cerebral lifestyle;  hours of sitting amid piles of books, taking notes, watching and listening to media, researching professional journals, and writing their own bodies of work to extend the collective knowledge of the subject they have chosen to focus upon.

If you’ve already earned your Bachelor’s degree, you will probably still need a Master’s degree in the subject you want a doctoral degree in before you will be considered for admission to that level of graduate studies.  Still, there are some people who enter a PhD program with only a Bachelor’s degree.  It all depends on the program admission policies at the graduate school you have applied to.

Here is an infographic that details some interesting facts about PhDs.  Click to expand: