Why so may ...bux sites?

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So ive recently joined neobux, Upbux and palmbux and i think there are some more that i haven't joined. But anyways, they are all mainly the same layout and stuff so i take it they're all made by the same people. So i was just wondering why? why do the make all those different sites? why not just have one main one? because it certainly makes me question whether they are legit or not. Thanks :)