Why Knight of Cups poster look like that?
It has some Palm tree & Pyramid on it.
Another poster here makes sense & suits to Rick role.
I would assume the palm tree is used because the movie takes place mainly in Los Angeles and Las Vegas - 2 places that contain lots of palm trees. Furthermore, the movie's title and plot are based on various cards from the Tarot card deck. The tree also looks similar to the Belgian version of The Tower card seen on the Wikipedia page. Perhaps that was a common depiction?
I was thinking that the other circles might represent other cards, though it's hard to tell from the small image above. The yellow one behind the top of the palm tree could be the moon. I can't read the writing around it or the one with the triangle in it, so I'm unsure if there's additional meaning.