Fighting in a war is serious. Playing a video game is not.
In war, you have a high risk of dieing. In a video game you do not.
While in war you see your best friends get shot an killed. In a video game you do not.

When you play the video game you have a great time. Whether you are playing alone or with your friends. It can cause a big competition, laughter, and a great bonding experience. If you and your friends get tired of the game you can pause it, go get a snack, maybe go play outside, and then return whenever. But,playing the video games that imply that you are in the war are ridiculous. If you die, you start over. If you make it through the game without dieing, if puts the mentality in your brain that you could survive the real deal. In war, you have to be fit, active, strong, and ready to serve your country. Sitting on your couch does not prepare you for that.

In war you dont get to take a break. Most of the time its not a great bonding experience or much laughter. It is serious and you put yourself into a great load of danger. Forbid you die, but if you are killed in the real battle, there is no restart button. You dont get to use your next life, you are done. Gone.

The graphics on a video game is brutal at some points, but you move on and you go try and kill the enemy.
The graphics in war arent graphics. It is the blood from your friend. Another soldier.

The mental piece of it all is very opposing.
Suppose you are playing a war video game, and your friend is a fellow teammate. If you are playing and your friend loses his last life, he sits there and watches you finish the game in hopes that you will win. If it wasnt in the video game, you friend would be lying there in pain until he dies. He wouldnt be cheering you on while you try and complete your tasks.

"Oh its not that bad, we can start a new game and forget about us being killed"
No. That is the wrong message. The war does not hand out redo's.

They should not exist.