I'm a teacher and most of my students destress with video games. I've also been a gamer myself, so I'll offer my thoughts here:
Games exist primarily for training, sharpening, and leisure. If you look at animals, for example, the young use games to learn valuable life skills.
I think if games legitimately fulfill any of these functions, as preparation for or relaxation from, life, they are a net good.
The real problem seems to arise when games begin to replace some elements of life. School work is left uncompleted, for example, or valuable training and reading is neglected in favor of games. Perhaps someone even settles for a substandard position in life because they find their satisfaction in games. The reward comes in the virtual world, because fear of failure fills their external world.
Speaking personally, I find as an adult i have turned to video games when I have a very difficult and stressful job, and lack the energy to pursue more meaningful and rewarding activity, such as reading or language study.
I'm not sure what to make of that. I enjoyed the games, and i don't think it was wrong to do so. But I also wish it could have been different, and the job hadn't taken so much out of me, because there were better things i could have done.