Steve, IMHO you do seem to make a fair general point here on Internet-only retailers and in favour of bricks-and-mortar ones, but let us not forget how useful online shopping is when you live in outlandish areas or where there are no retailers at all carrying what you look for. Of course unauthorized dealers are a different thing altogether, I think the comparison should be between authorized B'n'M ones (who may also sell online) and online-only ones.
Coming back to the original point, I agree with you a 50% margin is way too much for most industries' retailers, still if there are some industries that come near they certainly are the luxury ones and the luxury ends of standard ones.
Cheers.
Fabrizio