Hmmm... not to be controversial. But I firmly believe we can make a good income from being comic artists. And yes, it is my dream. Or rather I should say, goal. And I too have been dreaming of creating comics since I was 7.
However let me explain what I believe it requires.
Firstly, you need to have something worthwhile. I don't believe it needs to be the uber best thing that is going to revolutionise graphic novels and change a generation, but it does have to be good. By that I mean it has to be professional. A reasonable number of people have to appreciate what you are doing. This means we need:
(1) Good art - of whatever genre you are in
(2) A worthwhile message - that fits the medium, whether slice of life or long form
(3) Persistence
(4) Communication skills
I would say read books like How to Ignore Everybody and 39 other ways to be creative, for some inspiration.
I think some realistic expectations and numbers are also very key. We live in a world where it is even easier to be a cartoonist than ever before. We have platforms like Patreon, Kickstarter, Amazon, etc which allows us to bypass the former gate controllers (i.e. large distribution houses such as Marvel, newspapers, etc) to connect directly to a fanbase. The game has changed.
Now for some numbers. Your living costs are of course going to be different from mine but that's fine. I pin my idea of US$4000/month a pretty decent starting point for anyone. It takes most people a good 3-5 years of quality and consistent work, to gain a paying fan base that can earn them that. Those years are spent looking for the TRUE fan. The one who will pay money for your work. The magic number (and I attest this to be true by simply observing numbers on Patreon) is 1000. Okay okay, it could be a little more and in some cases a little less, but that's where it sits. 1000 true fans. And that's a good number. It's not small, but as I read on a blog article, you can count to 1000. It's not 1 million or even half a million. It's 1000. That is very achievable.
So the next question is how are we going to survive the 3-5 years of quality output to get there? That's something you need to strategise for. Yes, it certainly means for a lot of us a part time job. Some times a part time job we don't particularly enjoy. If you're a single, young person (I am a husband with a son and a mortgage) then it means you can be careful with your living expenses. Etc etc etc. The important thing to remember, is you've got a goal now (not just a dream). And because it is a goal, you can plan, structure, and build towards it. You can gauge how much work (and suffering, that's why its called passion) you need to get through it.
I wish you the best. Keep your feet on the ground but your head in the skies.