Getting into RPGs tends to appeal to higher IQ types, mostly 110+ (though older systems are more playable at median IQs); they also require fairly high literacy. This restricts the market compared to computer games; it always has and it always will. Plus WoTC have tended with 3e & 4e to cater strongly to a crunch-oriented gearhead market; my player who builds battle systems for Lockheed Martin IRL loves 4e D&D!
5e seems a bit more accessible to IQs in the 105+ range, but quite apart from accessibility, the very pastime of fantasy in-character roleplaying generally only seems attractive to a minority of the population, mostly within the higher-IQ part of the population. Nerd is cool, but high IQ nerds will always be in the minority.

5e seems a bit more accessible to IQs in the 105+ range, but quite apart from accessibility, the very pastime of fantasy in-character roleplaying generally only seems attractive to a minority of the population, mostly within the higher-IQ part of the population. Nerd is cool, but high IQ nerds will always be in the minority.