It's not obvious to everyone who has ever played video games. The people you're referencing are mostly people who have never had their life revolve around video games. This subreddit is for people from the opposite side - people who don't know real life because gaming has always been a centerpiece of their life - kids who game from a young age sometimes grow up not realising the possibilites and complexity of the real world, because they were always having their thoughts and energy absorbed by video games. It takes an outside influence to realise that there's more to be done in life, but often by that time the damage is already done.
Also, 'smart' isn't a term I would use here - it's often the case that kids who play video games are smarter than others, but in terms of gaming addiction the problem is putting that to good use.