Bounty hunting can never be a full time job as it is an uncertain hunting and no one can guarantee that a bounty from a project will yield anything from that project.
Actually, everything in this world is uncertain, so I can say that Bounty hunter could be the main job for those who have the ability to see the best opportunities. Yes, talking about uncertainty, of course all jobs are also uncertain, because we could be fired by the boss at any time for illogical reasons... our business could also lose customers without us realizing it... so nothing is certain.
I see that there are still people who live off the coins they get thanks to their completed duties as bounty hunters... that is proof that there are still people who maximize the potential that exists in this realm.
I don't think that this can happen easily, especially if you are a regular employee on your job. Whatever happens, you can't just easily get fired by your boss. Also, if you think you happen to think you are incorrectly removed on your job due to wrong accusations or anything that you think is valid reason to remove you, you can fight for your rights.
In every job there's a contract they must follow, if you are a regular employee there's no final date or termination date included because you can work in the company for so long, that's why it is called a stable job. It's not the same as contractual employee who have a short term period of work inside a company.
That's why you can also often see employees staying in a company for 5 years, 10 years, or more than that.
It is still better to have a stable job, this is not uncertain and enough reason to treat it the same as bounty hunting. Bounty hunting will never be advisable to think of it as main job.