That is the big question, isn't it?
A spiritual friend once talked about the meaning of life, and the first thing he said was, "What is your motivation?" His meaning was that if your motivation is not pure, then you need to reexamine what you are doing and try to do something on a higher level. In other words, if for example your motivation falls into the category of greed, it's not very high.
In art the greed motivation would likely be someone who is churning out cutesy little cottages lit up with light and surrounded by idyllic flowers and making a bundle, all the while selling out to the real talent which may lay within that person who is a good businessman. Or maybe it's someone churning out dozens of geometric compositions. Is this wrong? I don't know, as it is a way to make a living. Mondrian, I hear, made money through selling paintings of flowers. But he never let go of his direction as to what was important to him. And Van Gogh sold only one painting in his lifetime. Again, he was someone who had to paint. So in an odd way I've beaten that record at least on the financial side. From the past, I see I have done best selling paintings of pets though I tend to do these only occasionally.
I too feel driven to paint and make art. In a way it doesn't matter to me whether I sell -- but I'd like to sell the older ones, the ones that are no longer haunting me as much as the newer pieces. It gives me happiness to place my older work with people and then see them later, when I have sort of forgotten them. It's like writing a poem then, you see them much later and say, "Why that isn't bad", and realize that perhaps you never really saw it, at least not the way you see it now.