It is worth remembering the year 1492. In 1492 Ferdinand–King of Aragon, Naples, Sicily, and Valencia–and Isabella–Queen of Castile and León–gained sovereignty over the last Moorish bastion in the Iberian Peninsula. Grenada at that time was as Arab as any city in the Middle East. This is known as the Reconquista.
Just as importantly, in 1492 they issued the edict that expelled the Jewish people from the realm. Converso Jews who remained eventually fell victim to the Inquisition. These moves by the Crown and the Church may have greatly contributed to the eventual downfall of one of the richest empires the world has ever known. This expulsion of most of an intellectually inclined and commercially talented population began in the same year that empire was born. The murder of the remaining in later years completed the process.
There are many historians who would scorn that proposition as sterile speculation. Everyone seems to be of one opinion about this, however. The immediate and proximate cause of the eventual demise of the Spanish Empire was the propensity of the Spanish kings in later years for fighting war after war in Europe, wars and more wars that not even the combined treasures from the Viceroyalty of New Spain, the Viceroyalty of Peru, and the rest of the empire were sufficient to finance on a cash basis. All of it pissed away, and the Crown left wallowing in chronic debt.