I know a lot of people that spend many more hours than they are paid for working. They do this for a number of reasons, some people feel that it advances their career by making them look dedicated whereas others feel as though they are making a difference in some way.
The big thing that they are missing is that there is really only one winner in this equation and that is they employer that they are working for. Their employer is getting time and work without having to pay for it. Them working longer hours their employer doesn’t need to pay as many people for the work.
The loser of course is everyone doing the extra hours. I have fallen into this trap more than once, I have in the past worked on teams where it felt as though working longer was expected. Whenever I have done this I have suffered for it mentally and physically, I notice that I get sick more often (I never usually get sick).