I have no experience as a professional or technical diver. I have read on this board about this issue before (do a search) and heard some horror stories.
For what it is worth, points to ponder:
1. Talk to active professional divers and get a feel for what is real and not school recruiting hype.
2. What is the real wage paid in the field?
3. What is the real demand in the field (will you be able to get a job)?
4. What are the working conditions?
5. What is the average years you will be able to work and what, if any ill effects will it have on the body long term (I am told this wears on the body something fierce)?
I recall reading on this board about one person who quit a well paying $60K or so a year job, spent over $30K getting trained and landed a $24K a year job as a professional diver. So look well before you leap. Diving for a living is not like diving for fun, it is your job, and you dive in all kinds of conditions and weather and often in decompression required mode. I have heard stories about how the schools promise the moon, great pay, tropical work sites and deliver low wages in cold water.
If you are talking about being a dive instrucor, well that is different. From what I can see, and hear from talking to dive instructors, it is challenging making a living in the field with out some other primary source of income.