I frag:
-for the money (or trade), although it all goes straight into the tanks, I don't frag much on my DT anymore now that I have my frag tanks. I like to leave it untouched, but wouldn't worry if somebody wanted a frag, I would be happy to cut a chunk off.
But also
-to promote FOWLR hobbyists to adventure into the sps/lps realm ($5/freebie starter frags)
-to reduce the harvesting of wild stock
-to fill the 3 tanks in my basement that I convinced my wife I needed
-because with multiple frags of a colony I can keep my favorites in a couple of tanks in case of a crash
-but mostly, because it is cool to see them grow and plate out on the frag plugs! I think of it as SimCity, but for Reefies, and instead of looking at the computer screen, you get to reach into it
Dan