So far as live performance goes, being in a dedicated wedding cover band can be very lucrative if you are in a decently populated middle/upper class area.
There are guitarists on Twitch who regularly get 1k+ viewers on their streams, and that probably equates to a fair chunk of change given all the ways you can monetize your streams on Twitch. Alas, most are metal guys, which I find pretty tired at this point, but that’s another topic.
I supported myself for a dozen years teaching, the hourly wage is great but it’s not realistic to expect a 40-hr week. Downside was I always felt there was something I should be working on for a student, and you have to be prepared for a ton of students who view it as an activity; adults who just want to chat guitar, kids whose parents just want a break from parenting.
Honestly I’m much happier working a regular job and playing for the sheer fun of it, but to be clear that’s just my experience; if you decide to pursue this my advice is to really, really work hard in the first year. Give it your all and if you decide it’s not for you, there won’t be any regrets later. All the best, cheers.
EXACT same experience I had.
@Moje and @joebegly just out of curiosity, did you guys have (or later get) education in non musical fields?
It’s funny, every now and again I think of what things would be like if I had a ‘job’ but I have no idea what I’d qualify for without going back to school for 6+ years! Not that it’s a super serious thought, just crosses my mind sometimes.
Re 40 hr workweek, it can and does definitely turn into well more than 40 hrs if you factor in prep, scheduling, other admin, marketing, biz development, skill development, research, ‘customer service’, ‘new client onboarding’ etc etc, and business wise the rates have to reflect that to be sustainable.
And there are also a lot of business models possible besides just teaching independently and giving one on one lessons, for example teaching group classes, hiring other teachers to teach, teaching online with memberships or courses, or combining these things.
I was was a composition and theory major with a concentration in classical guitar performance. I did initially minor in education, but the “minor” at my school was so bloated it was essentially a dual major. In my second year I did practicums where I went to a school to observe a middle school band teacher and decided that type of job was not for me 
So I doubled down on the theory/composition aspects of the major.
Once I learned music in general was not going to cut it for me career-wise, I did take 3 classes in computer science, with a concentration on web development. My friend from my rock/metal band days hooked me up with a (not paid!!!) internship at a web development shop that lasted about 10 months before I got hired, part time, low wage. It did take about 4 - 6 years in the industry before I had full time, decent paying work. At that point, I stopped giving guitar lessons (which I was doing heavy-part-time while learning the programming stuff).
I should mention I feel really blessed/fortunate that I could even make a move like this. I have a very understanding wife who was on the same page with me, and at the time we didn’t have children, so we could really ‘rough it’ while I was transitioning careers and not bringing in much $. I know there are plenty of people who’d love to change jobs and don’t have the same flexibility I had due to family obligations. Yes, I worked my @$$ off to get into another field, but at least it was an option for me. 
I won the lottery there.
Yep. I was ‘working’ well over 40 hours per week when I gave lessons full time. It was through a mom-and-pop music store, and they set my rates. They made sure I got top dollar for what they were comfortable charging, but it still didn’t equate to livable income.
Certainly, if I would have been more creative about the ‘business’ side of things I’m sure I could have offset the low annual salary I had doing only music. I just chose to put my efforts into a different career instead. win-win really because music is still a big part of my life, just a ‘serious hobby’ part and that fits in better with the decisions I ended up making…since now I do have family obligations, which happen to be my favorite thing about being alive Also, being a former (failed??? lol!) composer, my software job is a great outlet because there’s a ton of creativity with programming since there isn’t just one correct way to do things.