gktscrk answers the question directly but, although it is true that there were legends and fears, and simple minded sailors, it is absolutely false that the elite did not expect to find anything valuable beyond the Bojador, or that only India was a valuable objective.
How significant was the Fall of Constantinople as an event leading to the Age of Exploration?
Read specially the answers from me and the Pieter Geerkens.
In short:
- The Portuguese already knew that Gold and Ivory would be found on the coast of west Africa. And that if they got that trade, the Moroccans would lose it. Even IF a way to India could NOT be found, they had enough reasons to go.
- The King had great income as Great-master of the Order of Christ, and he could not just pocket the money without loss of face: thus the navigations had stable administration and financing.