Once you get that there are tons of experiences, truths, feelings, memories, emotions, beliefs, etc., that can't be adequately expressed in words, it begins to make sense that we need music, dance, sculpture - all the arts - to address an unending array of interior realities that are simply too rich to be fully understood and defined.
To experience abstract art we need to engage our hearts and minds, our imaginations, otherwise we only see the surface of things.
So why don't people buy art? I am beyond caring. I am way to busy making art!