I wouldn't worry too much about what your friend thinks about 3D images. He isn't going to change the fact that CG images continue to expand to more and more areas where traditional photography has ruled. As someone who has been shooting photos and using photoshop for a very long time, I can assure you that they are not capable of reproducing every 3D image you see. Take a look at the 3D CG Choice Gallery at CGTalk and ask your friend to reproduce a few of those images.
Here is some more on the subject -
http://www10.dcccafe.com/nbc/article...ticleid=261557