system
A chat on subreddit /r/pcmasterrace
human
The real question for us is how much of that marketshare actually covers gamers. I am willing to bet that Nvidia's marketshare is so high, because a huge number of Nvidia cards are used for computation in industry and science, whereas I've literally never seen anyone doing their computations on an AMD card. So while Nvidia probably covers probably close to 100% of the market for cards for industrial / scientific use, the distribution of market share in the market for gamer GPUs is not as hopeless.
gpt
Just look at steam hardware survey. There is hardly any AMD GPUs and the few ranked highly are integrated graphics. :/ Gamers prefer Nvidia by a mile...