I can't speak for the others and know little about my new found hobby of MD'ing, but, I DO know that I enjoy it immensely! I haven't even found a piece of copper, gold or silver, yet, but, the stuff I have found has, indeed, made this hobby addicting. I get a thrill out of getting a target, digging a bit and spotting a small metal disc in the dirt! Then to determine it is a penny, nickel, dime or quarter makes it all worthwhile, personally. We aren't as fortunate as you good folks in Oz or New Zealand, with your $1 and $2 coins and it seems like your populace is quite handy a dropping them!! Not to mention, you have dirt that can be dug with a trowel. My area has mostly red (iron ore) clay that is hard as concrete when dry and has the characteristics of paste/glue when wet!
MD'ing is something I can do in my old age and it is pretty good excercise.....walking, kneeling, hacking at the 'dirt', getting back up. And, one of these days, I'm going to find something older than myself! I never did expect to recover the money I have spent on detecting equipment with my finds, but, as far as I am concerned, they have paid for themselves with the fun I have had already!!...........and,who knows?, I guess I could find that 1916 D dime on my next hunt!!