I'm not entirely sure how much help this will be but here's my life plan!
I'm in my third year of a 4 year Zoology degree at the mo and plan to study Vet Medicine when I graduate. Eventually I want to run my own craft business but I want to keep it small-scale, I don't want it to become my full 9-5 because as someone has already pointed out, you lose some of the enjoyment when it becomes something you *have* to do.
Being a vet is something I know I will able to happily work as until the day I retire and it brings the added advantage of being a reasonably well paid career path, meaning later on when I begin to serious think about selling items I make, I'll have a bit of financial backing behind me. It also means that if I try to set up my own business and it falls on its face, I still have vet medicine bringing in the money. It's less critical if the craft side of things takes or not.
So I guess my advice would be to work out what job you would be happy in and then maybe think about doing craft on the side. If you find that your craft business takes off you can go part-time on your 9-5 job to give crafts more time or even eventually give up the 9-5 if the craft business is successful enough. It makes it less stressful if you're not completely relying on your abilities to sell things you make.
Good luck with it all