I had to uninstall the windows games from my work PC. I had 13'000+ games of freecell completed, countless games of tetris, and solitare.....
It was a major problem for me. On a couple of occasions, I specifically didn't answer the phone because I was playing a game. In fact I was annoyed at the distraction. Not a good work ethic, and an easy wasy to build anxiety.
My friends all got into world of warcraft as I was getting into personal development, and they all chipped in an bought my a copy of the game, with an upgrade pack. I thought about it for 10 minutes and handed the game back to them with apologies. I just knew that it would occupy too much of my time, and as Steve says time is one resource that you don't get back.
For me, playing games were a distraction to the pain that was my real life, so it was an easy for me to become addicted. The other point to consider is that as I was playing more and more games, I was telling myself that it was a harmless activity, it didn't cost any money, it wasn't doing my body any harm, it made me feel better..... but the cost on my time was massive, which in turn affected my relationships, my work, my friends, my fitness, etc etc
Most things in excess are detrimental.