No, that's a bad idea. Not necessarily depending on talent of the artist, but just because those kinds of profits can be so sporadic. It's best if you at least keep a steady source of income if you want to make money off of commissions.
It's much more difficult living off of commissions than having a pretty stable part-time/full-time job. I would say still go for both if you can-- with the part-time job open AT LEAST for back-up. Trust me, in order to even survive in this world with art talent, you not only have to be on top of getting work completed for customers, but be able to work in a group that can be something like a part-time, full-time job for yourself .
Hoooo, no. Commissions are good for EXTRA money, to have something on hand, but not as a main source of income 'cause then you have no idea how steady or slow it'll come in. In a boring job, at least you KNOW you're getting paycheck on payday. Commissions run on a person to person basis, and that person can cancel or not pay or the commission may take a while and all kinds of factors that could get in the way and leave you broke in the end.