I'm not even a DM yet, but I am going to be an instructor by the end of the summer, I am going to go up to MSD-T and then start teaching on the side.
I think it is all about approach, I am a personal trainer (do pretty well at it) and I plan on wearing dive t-shirts every day, having double sided business cards, and I am recruiting my girlfriend to help put up flyers, etc for the scuba business when the time comes, its all about effort, you can make a million bucks selling pet rocks, but you have to get out there and SELL PET ROCKS...
I plan on having 10 students a month (teaching on Saturdays and one evening a week) One evening a week is make up day, and saturday is THE DAY. No exceptions, etc. I am going to have a very uniform program in place (unlike a lot of dive instructors that catter to the student, just so they can have a student), I am going to get students through personal training, I train people to live active lifestyles, diving is a great activity, just loading the tanks up into your car and heading for the beach and kicking your feet a little is 100 times more than 99% of the population does everyday... On top of that I am going to make arrangements all over town so I can stay busy...
Keep the cylinder full, never worry about Having students, worry about teaching them...
I would think that if a dive master wanted to make money, they would arrange special trips, both local and exotic and advertise them a year in advance and do anything POSSIBLE to book themselves solid... you can't expect someone to hand you clients, if you can make $50 a day as a DM with someone HANDING your clients, then you should be able to make $1,000 a day with a GOOD effort.