I'm inclined to suppose there are some hidden (i.e. unconscious) reasons.
If you like to regard a human person as not to be homogenous at all but instead been put together from some facettes you don't overlook, then you might find out that some of your components (or one of them) has the power to stop you realising this plan (at least at the very moment).
One of those aspects you gave yourself: the need of fast producing income. But there may be others, and I'm thinking of such personality components who like to query and to insist on meaningfulness of living and doing.
Did you ever consider such a possibility?

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I'm well aware that maybe my artwork isn't going to sell particularly well

You gave one answer already yourself - the economical/ psychological one.
But I'm pretty sure there is some more in regard to spirituality / philosophy / belief.