If you want to compare 3DX to volley ball, or even football/soccer/basketball, it's like comparing apples to oranges. The only thing they have in common is that they are both fruit.
In football when the quarterback fakes a throw in one direction and actually throws it another player 50 yards out on the other side of the field the only thing lost is a possible touch down.
I have heard people use the excuse "It is just a game" when they have lied and cheated and hurt many. They think that because "It is just a game" that it gives them permission to be mean, dishonest, and completely unethical as a means to get what they want which is usually much more than a touchdown in a football game.
There are many on here who play head games in order to gain attention. I am not going to name names but I am sure you all have met them too. The woman who has had 7 battles of cancer and won them all in under a months time each time. I find this one amongst the cruelest. Some use it to get out of relationships and fake their death only to begin again the next day on another avi. Just a game? To the person who has stayed up all night holding their hands, spent hours encouraging them to stay strong, perhaps even sent money to a go-fund me account to help pay for medical bills, cried with them, prayed with them. Put their own real life on hold in order to provide every possible support they could. And then have to hear "So what? It is only a game" is quite insulting.
There is no age group limitations to this excuse. I've seen those of all ages be disrespectful and cruel, then turn around and mock the one in tears saying "Its just a game." I don't care what game site you are on as that has very little to do with it. When a person who does these things says "Its just a game" it is an excuse for bad behavior that has deeply hurt someone. And THAT is NOT just a game. That is real life.
As to sex and the 'I love you' that many say after a week, my advice is to run. No one can possibly love you after a week. Lust? Absolutely. But if you believe them and you get hurt then it's your own fault, but it is still not 'just a game' to the person who foolishly believed a lie.
The phrase "It is not just a game" would not be used so often if the phrase "It's just a game" was not used just as much.