Depends on your definition of better. The fact that Adobe's revenues were over $3 billion would indicate that quite a few people would define "better" in such a way that Photoshop is better than GIMP.

photoshop is better than GIMP. paint.net is a great free alternative but windows only. in relation cheap is better than expensive, and any alternative that challenges a monopoly or overpriced incumbent can be a very good business to start and a product/service that many people will happily try out.