There are many types of diving which can be performed. Most people will remain hobbyists who enjoy getting into the Deep Blue when they can. Others may decide to become a Dive Master or even an instructor.
Then there are the hardcore divers who decide to completely embrace the underwater experience and devote their lives to it. Teaching other to become instructors or venturing out into the commercial dive market can be very rewarding. It all comes down to whether you like or love diving.