A lot of people don't want to feel like they are behind and will buy the new consoles out of habit. They do not like to wait, and so they shell out for their favourite(s). I'm not sure why the PS4 is winning, but the Wii U also has the issue of not exactly being next gen, not offering a worthwhile library, and having its core demographic be uninterested and unfamiliar with the console generation cycle. I know it is very early days still, but the three of them are only like 170% the sales of the Dreamcast​.