how come this file is so large >
Not all photos taken with the same camera at the same settings will have the same file size. For instance, in-camera NR and Sharpening increases file size.
Modifying the image and saving using Photoshop and other programs increases file size. When you save a image on photoshop, you get a "image option" slider bar. Set it to 12 and file size is increased. Set it to 0 and you will see it will go into the kb range. This was the Jpeg compression I was asking about.