@nprofile1q... it might be a combination of both. But I think there are a lot of artists who don't have jobs, or their commissions are their means of income which allows drawing constantly. If you have a job and a life outside of art then time is definitely something you have less of.
And as someone else said, some artists are just wired up for it. I had to practice for decades and it still takes me lots of time and effort.