Why was the Portuguese king not interested in Columbus’s proposal to search for a western route to India?

Christopher Columbus spent a rather large segment of his life after leaving Genoa in Portugal. At this time, the Portuguese were equipping expeditions to find ways to rich India. They assumed that they would come to the Indian shores, rounding Africa from the south. By the time Columbus proposed his project of reaching India along the western route (around 1480), the Portuguese had already descended below the equator along the coast of Africa. And, although the king first became interested in the idea of ​​Columbus, but then abandoned it, because his country had already explored the eastern path for too long and considered it correct.