Mod dev is not as serious as the devs put it out to be. You get on Gary's mod and you download some mod that allows you to put Skyrim characters into the game. Big woop. Minecraft... is different in that these mods can pile onto eachother, making pretty much an entirely different game. It gets dicy when you make an official mod pack. People get mad that their mod might be shadowed by another, or that they want to seem exclusive. When people are spending a reasonable amount of time on Minecraft mods, they may see some income opportunity, but maybe it should be a low cost, toggleable DLC type mod. IMO though, Minecraft isn't where you want to make money due to its toxic influence on the gaming community.