Why is it frowned on to spend your free time playing video games?

I am 20 and I have always believed that since it was 2013 playing video games was a normal thing. But one thing that I have noticed form non gamers is that whenever I would sometimes play video games non gamers would always comment how I am "wasting my time" or "not gaining anything" or "not being productive" While playing video games.

For Example: When I started college I have always thought that playing video games was a socially acceptable thing to do now. But when I went into one of my math classes one of my teachers who is in her 60s made a comment that just made me tense up. She commented that we should delete our games because she viewed them to be a "waste of time". She even made a remark on how weird it was to play video games for a living. I was thinking she was either talking about video game testers or YouTube lets players but her last comment bugged the crap out of me. However, the next day she was showing us a link where I can watch movies online for free. SO to her, movies are a acceptable pastime to engage in. However, spending your free time playing video games is viewed as a "mindless" activity. Why is that?