I've had several former students become instructors. And when they asked my opinion I'd always begin with the same question ... "why do you want to become an instructor?" The response was usually something along the lines of how much they loved diving, or wanted to "give back" to the community. And that's all well and good, but to my concern it's the wrong answer. You should want to get into teaching because you love teaching ... diving just happens to be the subject matter. If you do it because you love diving, then what happens when you are faced with the reality that you're diving for work now, instead of for fun ... and the circumstances for making the call to go diving or not are driven by someone other than yourself. So consider carefully, because once you become a pro, diving becomes your job rather than something you do for recreation... and that accounts for the high turnover rate among those who achieve professional status. Many of those I know who went into teaching only taught for a year or less ... and some not at all ... because the reality of the program didn't match their expectations going into it.
And there are many ways you can "give back" to the diving community without gaining a professional certification. Volunteer programs abound, and many of them will help you improve your personal skills in ways that a dive professional program will not.
As for what made me go pro ... suffice it to say a dive shop owner who recognized my affinity for teaching and made me an offer I couldn't refuse. The course cost me very little, and the money I saved on the purchase of my first drysuit as a pro more than made it back. Effectively, it was an economic decision that just worked out well in other ways ...
... Bob (Grateful Diver)