Ok Scuba Diving, pros= very fun, cons= not enough time in the water
Risk = risk and danger is associated with every activity you do, if you follow procedures that are taught to you, you will be fine. There is an old saying "there are old divers and bold divers, but no old bold divers."
As far as going from open water to diving, as most people have put i would hold much creditation in that. Start out with your Open water card, then get a few dives and progress to Advanced Open Water then youll get your rescue followed by divemaster then followed by instrucutor. You can not earn any money based on diving unless you are atleast a divemaster. Once you hit divemaster level, you are then required to carry insurance. same with instructor.
I myself have been diving for 6 years, and now am working on my divemaster training. I have about 300 dives in, some have had mild emergencies, but these just make you a better diver. They are things to learn from. If you do not have any mild emergencies, you cant teach people the best way to correct the problem, or even answer some of there questions. Instructing is not for everyone, imho only people who feel really compelled to passing on the love of the sport are the ones who should teach.
As far as money, most people have said it right. You can make money from instructing, but its better off if you keep as a part time kick. Most people who live on just instructing teach more than open water classes. For example they teach Nitrox, Advacned Open water, rescue, cave diving, specialties, trimix, etc. The higher the level of certifications the more the classes are, therefore the more money you can make. But agian the higher the level of certification, the more time and more strict the agencies become on their instructors.
I definetly think you should enroll in an Open Water course and let the journey of Scuba Diving take you where ever you want to go. Who knows you might absolutely love it and want to teach, or you might just love and just want to dive. But don't do it for the money, cus honestly there isnt much