Action game players make more correct decisions per unit time. If you are a surgeon or you are in the middle of a battlefield, that can make all the difference.
The average age of a gamer is 33 years old, not eight years old, and in fact, if we look at the projected demographics of video game play, the video game players of tomorrow are older adults.
We have a large amount of data that shows playing fast-paced games improves hand-eye co-ordination, the ability to focus on the task at hand, and your ability to make decisions, as gaming improves your brain's allocation of resources.
People who played action video games have better vision in the sort of conditions where there is not much contrast. It can make all the difference when driving at dusk, or in fog, in being able, for instance, to see a dog crossing the road in twilight.