Indeed in the US IQ scores are still going up, and video games have all kinds of benefits in terms of brain activity. However, the issue would be not whether video games make the player smarter or dumber, but rather the time spent by intelligent people on video games. That is time they can not devote to furthering their more significant talents. It is time not spent on learning significant skills. Can you imagine if we had video games in the times of Michael Faraday, da Vinci, Alexander von Humboldt, Nietzsche, Galilei, Goethe, Newton? Would they have happened or would they have spent too many hours gaming to learn the skills they learned?
After all it takes not just exceptional brains, but industrious productivity and hard work to create the works of genius we have seen in the past.
I know some extremely intelligent people, and they do not waste very much time on video games. It is almost like their powerful intellects propel them to develop their minds and talents, as they work on their careers and/or various personal projects. Not all of these people have advanced degrees, but they are all exceptionally gifted and enjoy applying their talents.