To each their own, and if anyone is happy with one guitar then more power to them. I think that over time I would be left wanting more if I had just one guitar. Different guitars have different sounds to them, so part of the fun of owning different guitars is the range of tones you can get. That's one of the main reasons I like to have several guitars. That, and I gig out regularly so it's good to spread the wear and tear across several instruments.