Masters vs. PhD

I'm going to be starting my masters degree in I/O psychology this fall. Right now I am considering eventually applying for a PhD because I heard from a family friend that this opens up more job opportunities in I/O Psych. But I wanted to see what everyone here thought as well. So, is a masters degree enough? Does a PhD really open up more options, or does it make you "overqualified" or is it only useful for people trying to get into teaching/research? I'm not 100% sure what my goals for the future are but I'm thinking more along the lines of consulting. Sorry if this has been asked before, I tried searching but couldn't find anything.