As a hobbyist who develops stuff for my own amusement and the occasional extra pocket change, I couldn't care less about supporting platforms that I don't enjoy using, even those platforms had a 99% market share. Vista and Linux fall into the "not fun for me" category, and thus are not part of my plans. OS X, and to a lesser extent XP, are fun for me, so they're in scope.
If I were trying to make a living from this, I admit I'd obviously either have to pander to the masses at the cost of my enjoyment, or find a lucrative niche. Personally, I'd rather keep my day job and sell 100 copies of something I enjoyed working on than sell 10,000 copies of something that was a chore to develop, while simultaneously helping to support the very platform that made my fun project into a chore.
If I were trying to make a living from this, I admit I'd obviously either have to pander to the masses at the cost of my enjoyment, or find a lucrative niche. Personally, I'd rather keep my day job and sell 100 copies of something I enjoyed working on than sell 10,000 copies of something that was a chore to develop, while simultaneously helping to support the very platform that made my fun project into a chore.