There are a lot of people that get into gunsmithing only to find out it's not the glory they expect. It takes a long time to develop a name, clientele, experience before you start making money and if you've got a family to support, it's only that much more stress.
Also, people think they can go to school and magically become a gunsmith....not so easy. If you're not very well mechanically inclined, this isn't the job for you. To even consider this career, you should already have some background as a machinist, be the guy that has a shop at home to work on cars or any home project, have some welding skills etc.
Simply put, if you want to do this because you think it would be cool, rethink the career move. On the other hand if you're the go to guy for your friends and neighbors home, hobby or vehicle projects and are OK with taking several years learning the trade before venturing out on your own, it's not a bad choice.
I was a gunsmith for a while and had more opportunity than most for machinery, tools, instruction etc. and still struggled to make ends meet. When the opportunity came along to switch careers and not worry about money, I took it. I still smithed for friends and referrals but never got back into the trade publicly. When business is good, its very good but when it's bad, it's almost zero.