There is another thing about paintings that makes it difficult for some to sell. This is a delicate subject. I tend to step on artistic toes when I bring this up. Many artists tend to think in terms of emulating dead styles and dead technology, forgetting how conscious those like Da Vinci and Dali were aware of technology and those tricks it can lend the artist to trick the eye. That is what we do. We trick the eye. We are illusionists tricking the viewer into a sense of perspective, luminance, and life.
As an example, I pioneered a method before computers made it so easy to animate a painting that was executed on multiple layers of Lucite. The layers were not only painted, but they were engraved, etched, and abraded to refract light to predefined ends as one changed position relative to the image and the ambient light. As one moves about the room what was static becomes dynamic.
We need to start painting beyond the canvas. We need to start thinking beyond painting when we paint. It was Dali who infuriated his master by lifting the paper to capture a beard as part of a sketching assignment. We all know who Dali is, because such a trickster. No one really knows who that teacher is, because too uptight to play our game.
There is so much available to us now. Not to use all available to us is the leading cause of artist failure.