Consider your long-term career goals. If you have a true passion for a specific field of study and wish to stay in the field of academia, a Ph.D. can provide stability. Ph.D. degrees do not guarantee employment as a professor, but having one can help secure tenure and makes you a viable candidate for many research positions.
Weigh the financial pros and cons of obtaining a Ph.D. Consider the long-term return on investment and by considering the price of obtaining the degree in terms of tuition cost and the opportunity cost from not working, as well. You should also consider possible fellowships that you may be eligible for when calculating these costs and also remember that the cost of a Ph.D. is not nearly as fixed as other degrees and that the time to complete the degree is dependent upon many variables, some of which are out of your control.
Consider your personal and family situation at the time you will be entering the program as well as throughout the program. Think about financial obligations that you have that could be jeopardized by the program running longer than expected. Also consider the effect on your family if you have children or a spouse or if you are about to start a family.
Think about how a doctorate degree will fulfill you as a person. Do you really need the degree or are you getting it merely for the status? If you are that passionate about it that you feel you need it then you have a higher chance of success in the program, but if you are merely seeking to obtain it for superficial reasons you may find yourself not appreciating the educational benefits of the rigorous work load.