Why are people selling their art so cheaply?

Well I just got back on DPW after many months of being away. I was hoping it would help with my sales which have never been worse. But I can see now that it’s not happening here either. I haven’t even come close to making a sale yet. I’m a solo operation, like many others are, so it’s not an easy thing to do.
I’m finally getting into a gallery at the arts district downtown and hope to make some sales there. I think online sales are tanking since there’s everybody and their cousin selling art online nowadays, it’s so hard to even be seen at all. Well unless your a marketing expert of course.