Because your situation applies to everyone here? I invest a lot of my overdraft and extra money into bikes, bike bits, bike clothing, food, etc. because: a) I really enjoy riding it b) I ride it a lot, so this investment makes sense c) I (will) race with it, so it makes even more sense if I want to win. A folding bike is meant for commuters really, hence it won't be as strong or as good at handling trails as a mountain bike. You're a gamer, is there really that much difference between a 4870 and a 4850? Why bother spending the extra money?