Photography and framing complement each other. Getting a basic setup and learning a few stock lighting arrangements can give nice results. Plenty of books on how to do it.
Don't confuse all photographers though. I do a lot of sports. No team and individual stuff, just shooting during the games using the same gear for TBall and High School as I did for NFL, MLB, NHL and NBA. I shot pro sports over the years and do the kids the same way. A lot more fun for me and I feed images to a number of newspapers as well. Also a number of schools, State Associations and whatnot.
As far as portraits, it is wide open. How good you want to be will determine your market..., coupled with how good you actually are. I shoot portraits with an 8x10 view camera, do hand coated platinum prints as well as silver B&W prints. What you get is the size of the negative, all hand done. Quite different from the portrait studios in our area. All work is on location with processing at my place, my darkroom, later.
Just as there are varying levels of framers, so too with 'Photographers". Anyone can buy frames and call themselves a framer. Same deal with buying a camera. Thirty years doing hack stuff doesn't make one good. Thirty years exploring, finessing and learning can lead to good work, but not always. Some just 'have the touch' and others spend all their time copying someone else or following 'whats hot', never developing their own style.
A good custom framer is different from the guy who slaps stuff into a frame and sells it. So to a good photographer from the 'photo studio guy'.
I got into framing because I was looking for more than the framers where I was at the time could offer. They didn't know how to frame an albumen hand coated print. They didn't know how to frame/mat an ambrotype or tintype. Some of them pushed specific frames because of the markup. Others didn't really want photography. So, I learned to do it myself. I do custom framing, specializing in photography. I send oils to a friend to do as I don't really like doing them and she does.
If you can make good portraits, try it. No matter the hacks in any business there is always room for quality. Just don't be surprised if some of the hacks make way more than you ever will if they know how to market. Photography or framing or whatever, if you can't market yourself you won't make much.