I honestly don't understand what they are plotting:

> So for example, the 74th-%tile in Competition among Hardcore gamers means that the average Hardcore gamer scores higher on Competition than 74% of the gamers in the full data set.

But together casual and core make up 78 % of the sample, so that the some hardcore gamers must have scores lower than the "hardcore average". Those hardcore gamers only make up 4% of the total sample, which means that 0.04/0.21 = 0.19 -> 19 % of hardcore gamers score lower than the hardcore average!

That's so skewed an arithmetic average is clearly of little use, but at the same time they talk about percentiles, so I don't know what's happening here, did they take the sample average and pretended it's the median?