Whether a PhD in marketing is worth it or not depends upon your career goals. The program can take 4-8 years to complete and is aimed at helping you build expertise and research skills. This post-graduate qualification can lead to a diverse range of career opportunities in the business sector. You can qualify for teaching jobs positions in universities, work as a business researcher, or even qualify for an executive-level job position in a corporation. The income level will vary from place to place.