Any job you have, people will complain. I worked a job making 2000/wk some years back and guys I worked alongside were making more than that, had three days off per week but still all I heard were complaints about the company that was providing wealth to their lives and 100% payed health insurance across the board.
You cannot do anything about what other people feel or act like. Only yourself, when i hear a coworker explain how bad it is, I explain how it could be worse and try to give positive feedback about the position and help them realize what they could do differently to make it easier on themselves. That or completely ignore them when theyre complaining.