I think the case is that when you start playing a video game you don't start with the intention of playing it for 10000 hours, you just keep playing an realize you have invested so much time that you may as well keep playing and become the best.
Most people who trot out that "10,000 hours" figure don't remember the second part - it's 10,000 hours of _meaningful practice_. Being the best at something, including video games, isn't something that you just stumble into.
Would you say that about someone who enjoys sports as a hobby? You say "may as well keep playing and become the best" as if video games somehow involve less skill or practice to become the best at than other hobbies.
I think it is mostly that video games are generally designed around quick gratification compared to most other activities, they are not usually designed to be your primary hobby (at least 1 game on it's own is not).
Throw a relative newbie into a first person shooter game and they will probably score their first kill in a matter of minutes, it just doesn't ask any long term commitment from you. I imagine very few people started out thinking they would become CS champions, more likely they found it addictive and played allot then at some point took it to the next level and joined a clan etc.
Contrast this with learning the guitar for example, first you have to buy $100+ of stuff that is only useful for that hobby. Then you will try and play some songs but most likely your going to have 10+ hours of practice under your belt doing boring stuff like learning chords and getting callouses on your fingers before you can reliably play even very basic rock songs at full speed.
The learning curve then becomes very steep, especially if you want to learn complicated solos and techniques but once you have mastered it then it is a skill that is kept for life. It is very unlikely that a new instrument will come out which renders your guitar obsolete.
All of the people that I used to play counterstrike with no longer play it at all or only play very occasionally. Contrast this with the people I know who started playing guitar instead (investing a similar number of hours) at a similar age. Almost all of them are still playing and are now very proficient. They are playing gigs and writing/releasing their own music. A few have even made careers from it.
Single-player games may be built around that, but multiplayer games generally aren't. Have you ever seen a newbie get thrown into a multiplayer FPS game? Unless everyone else is at a similar skill level, the newbie often just gets destroyed. Heck, the difference between my friends and I at Halo isn't even that great, and I usually only wind up with a handful of kills at best! (It's arguable that I might just really suck at Halo, but it's not like my friends are that great either.)
That being said, I still fail to see how this is any different from playing sports, or any other hobby. You try something new, discover you like it, do it some more, get decent at it, and then decide to take it to the next level. I've never been that addicted to video games, but one could easily argue that my current hobbies have (obviously) been more addictive for me, since I've stuck with them to such an extent.
It is true that video games do age quickly, but it's not the case that your skills suddenly become obsolete. When the electric guitar came out, did that suddenly render classic guitar skills useless? It's the same with video games - many of the skills transfer over within the same game archetype. It's why you see the same people winning at different 2D fighting games over the years. Despite playing a completely new game, the bulk of your skills are still intact. Sure, the specialization is gone, but that's part of the appeal.
Yes, but how many of those CS players actually invested time into _meaningful practice_ at CS? No offense, but just being in a clan is kind of like being a club sports player. Pretty damn good compared to the average player, but not the same at all as putting in the work to become world class.