Even If you have earned more than what you earn in your day job, I'd still say yes If that side job you have is not as stable as your day job.
I have into that situation before, but still I did not quit on my day job, because I knew nothing is more stable than my day job. I wasn't wrong though.
It would be very fortunate If that side job you have shifts into your main source of income because some may work unlike my situation.