As -=Larry=- mentioned, I don't get paid. The free air fills are handy and the discounts on gear were nice when still buying gear. But after a few years, I have enough gear to outfit several divers and have no need for more, so that particular perk wears out pretty quick.
Unless you live in a coastal area and plan to DM on/with a charter service, you won't even make tips. But DM'ing is one of the most rewarding things I do. To have a part in starting new divers, to see the wonder in their eyes and on their faces is something you'll never get over. The diving you do as a DM isn't the same as going out and diving for fun or going on a trip, but it can still be enjoyable
I doubt I'll ever go on to Instructor. Of all the Instructors I know in my area, only one dives outside of class unless it's a shop sponsored trip. They all have 'regular' jobs and all their spare time is spent teaching instead of out diving for fun. We (Beast and I) fell into that trap ourselves the first couple of years we DM'd. But after a while we just got burned out and viewed it more as a job and didn't enjoy it as much. We laid out almost a year and now it's fun again. We restrict out DM dudties to once a month, the rest of the time we dive for fun.
So think long and hard about it. do it because you love to share your knowledge and enjoy working with all kinds of people. If you got into it for the money, you're going to be sadly disappointed.