I am not at all involved in the vaporizer industry, but if I were you I would read up and talk to as many people in the industry as possible. This forum is an incredible resource for putting you in touch with those people. There are lots of great examples of successful small vapor companies (Dynavap instantly comes to mind, as it was crowd funded, and extremely successful).
As for designing device, a background in engineering and would be important. I would make sure you are well versed in Thermodynamics, fluid dynamics, and mechanical behavior of materials at the very least.
For manufacturing the device, besides money, you'll want to study manufacturing, and have had experience working in manufacturing before you take on a project of your own.
Marketing and selling the device is very important, but I know very little about that.
Creating and selling a product as a one man show is really something difficult. I can't imagine taking on that kind of responsibility, and I am in awe of the people who do.