For example, here in Colorado, the one picture a landscape photographer has to take (and will be judged by) is Maroon Bells. It's the most photographed spot in the state. There are weekend mornings where there is hardly room along the lakeshore for another tripod. Ansel Adams did a wonderful B&W version. Now why would anybody want to take another shot of it? It's been done to death. Anyone can go out and buy any number of truly spectacular prints, even print some off Flickr.
Well, it hasn't been done by me, yet. I've tried and failed. I don't care about all those other guys. I want to make my own. I don't want to sell it - who would want to buy it? I just want to take a beautiful photograph that does justice to one of the most beautiful places on earth.
Maybe at this point you need to tell yourself you are doing it for yourself. Just for the shear pleasure of doing it.