I only worked part-time as a waiter for a few years during undergrad, so I can only really speak from that perspective: I think that having a part-time job can be very enriching. As FutureHopeful? said, it certainly is interesting to work with people from different demographics. I also think that working a part-time job in the service industry really enhanced my social skills and understanding of how to work with and interact with others. A big plus was learning time management. That being said, a part-time job can be a big time sink that adds lots of stress- they're not always as flexible as a volunteer/lab position so when you have a big exam(s), you may still have work till late at night. You definitely will not be lost as as a person without taking on a crappy, entry-level job lol, but if you think you would enjoy it, you can definitely give it a shot!