Why were king ferdinand and queen isabella of spain willing to finance columbus?

The King and Queen believed Spain would benefit from Columbus' findings. For example, if he did indeed find a quicker way to the West Indies, Spain could and most likely would trade with them. This new trading partner would greatly benefit Spain and it's economy.

2686-2181 bce-- "egyptian civilization developed along the nile river in large part because the river’s annual flooding ensured reliable, rich soil for growing crops."

1069-664 bce-- "ancient egyptians developed wide-reaching trade networks along the nile, in the red sea, and in the near east."