It's far more difficult to gain recognition and get word of mouth going on the app store (due to volume), combined with the lower selling point as compared to desktop (for example $1 vs $15). People don't want to pay up front for games and the race to the bottom on prices have really hurt the little guy.

All graphs I've seen of sales on the app store show an inordinate amount of sales for the top sellers, whereas the tiers in the middle and below don't make anything significant at all.

Then go look at steamspy etc stats, even games 2/3rd's down the lists for a year's releases would have made a few thousand $ (as compared to app store where they might have been sitting on tens of $).

Either way, learning to code via writing a game is something I recommend for anyone, anywhere.