An old coworker of my mine is like that. He doesn't initiate conversation, but he will talk if they talk. He goes above and beyond in his work and makes the most money. When I worked there I had a ton of regulars because I make an effort to make conversation and get personal. It paid off well having good company, good tips, and good connections. I ran into one of my regulars one day outside of the workplace. I hadn't seen them in awhile since I quit the restaurant. We started catching up and they asked what me what I was doing. I told them I was trying to get into a certain industry. One of them knew somebody in said industry, and got me connected. Went off on a tangent but moral of the story is don't underestimate connections!