You're still going to be better off getting your Instructor rating unfortunately. The reason being is that a DM is primarily used to assist an Instructor with courses, help certified divers while on board or guide the dive for them. The Instructor can do all that plus teach a course if someone wants it. Most business owners are going to want the person that can bring them the most money if there is money to be made. They don't want to turn away guests because they don't have qualified staff to do what their guests are looking for so they look for individuals that are qualified to do everything that their particular shop advertises. Most dive shops do not bring in tons of money so they are always trying to offer more services to their possible clients. I have yet to see a shop only offer diving for certified divers and not offer courses and I've done a fair bit of traveling around the globe. I would say the one exception to this may be if you have a lot of experience doing mechanical work on boats or if you are a Captain. But then you would probably be hired to do just that and not DM for clients.
I can understand not wanting to spend the extra money on an Instructor course if funds are tight. Just realize that most of us that do this for a living are doing it for our love of the ocean, the enjoyment of the lifestyle it provides and because they genuinely enjoy teaching others new things and opening their eyes to this wonderful sport. Things can seem rather glorified from the perspective of a diver that has done a couple of certs and gone diving on a few vacations. I myself remember thinking after my OW cert, "People get paid to do this?" If money is your motivating factor, find another path. I'm happy to do 4-6 dives a day and make just enough to live in what most people refer to as paradise.