Well actually the human kind is an aggressive species. That's in their nature and for all eaternity it needed an outlet.
In the good old days of the Romans you took some gladiators, slave, christans, lions etc. and threw them in a pit and watched to see what happened.
To make it a bit more interesting you also made up some rules so the fight would take a bit longer than just mere slaughter.
Before the games, they had war to get rid of their surplus testosteron.
And after the games Western society more or less reverted back to simply enjoying war.
For just about any other culture in the world it is the same (there are a few exceptions, but they are scarce and mostly come from regions where live is so dangerous no extra loss of human live could be risked - as soon as life get's good war pops it's ugly head up).
These days we don't have immediate cause to fight, but in a large part of the population (not all, genetics gave warprone individuals a higher survival chance in the past, but now it is the opposite - society tends to lockup or send away people with too high testosteron levels, leaving the easy going types to be the ones getting offspring, so in theorie the people with low level testosteron should take over in time) needs an outlet for their aggression.
That's why it is often good for children to take up a sport like martial arts.
It sééms an agressive sport, but most children develop healthier and more balanced than they were before they joined.
These games you talk about are just a way of giving outlet to the high testosteron levels.
Actually they are not all bad - people that play games are able to focus on several tasks at once and are more controlled in their movements.
I do agree though most should be monitored when being used by (young) children, since their brains haven't fully developed yet and their perception of things is often different from the adult point of view. They are also not truly capable of making the distinction between 'a game' and reality.
That doesn't mean they will start to treat reality as in the game, but more that the game will affect their sense of security and safety in reality.
The ones that become so distorted in their view of the world as to do crazy things, are not so because these games are bad. There is just something wrong with these people to start with.
Did you know that most people that are a bit 'off' and do crazy things, have often been shunned in life, because people sensed something was wrong with them to start with, but that they go overboard, because they feel excluded, shunned, pitied or have been targeted and made fun off.
So the best thing we can all do is care for the people around us. Also the ones that are different. Not out of pity and certainly not out of fear.
But because that is what society is about: people together. In all their shapes and sizes. And only if all members of society truly feel they are a member of that society will they respect and cherish it.