Why did the Queen Isabella and King Ferdinand of Spain finance Columbus's voyage?

Queen Isabella and King Ferdinand of Spain financed Columbus's voyage in hopes of expanding their empire and increasing Spain's wealth through new trade routes and resources. They were motivated by the desire to find a westward passage to Asia to access valuable spices and goods. Additionally, they aimed to spread Christianity and counter the influence of rival powers, particularly Portugal. Columbus's promise of discovering new lands aligned with their ambitions for exploration and conquest.