You can make money – the skill is not necessarily having great photos – its having photos that others want to buy. Alamy sell loads to all sorts, not all of them are what you would call a great photo, its just that they suit what the consumer wants.
It could be a daft picture of a dog for a calander or a picture of a cloud for HSBS’s latest advert. One woman made 30K for a holiday snap that was sold to a large bank for its adverts. Others make smaller amounts for all sorts of random shots. Some make nothing, but either the picture sits on your hard drive earning nothing or you upload it and it could earn something.
The key is how you describe them, not the picture. The picture buyer / reseacher will use the words in the search for the image, not the image. Then once they have a collection of images then they will look for the picture to suit.