I bought Minecraft quite early, back when it wasn't such a big hit. Normally I do not buy games. But I'm all for free & open source games, and back then what the site said read or at least felt like a personal promise to eventually release the code. That is why I bought Minecraft. The game looked interesting, and I wanted to contribute to (eventual) open source gaming. I wouldn't have paid for it otherwise... and no, I don't actually play Minecraft.