It depends on your LDS, and what kind of time you have to dedicate to it.
My LDS has been known to hire folks who have entered their DM program, and has them working in the store while they work on completing their training. Some were hired as they were working on the rescue course, and were kept on through their DM training. I think it really depends on your LDS, and your relationship with them.
With that said, I have had a few friends that obtained their DM, and then did not have enough time in their busy lives to actually be a DM. They have the card, but not really the experience of being a DM. Giving up their weekends to assist with classes was just too much. They also seemed to realize that diving was a hobby they loved, and some of that love faded when it became a job.