The greatest mistake that Spain ever made was expelling the Jews in 1492. The Jews were the basis of the mercantile operation in Spain. With their departure Spain depended on the gold taken from Latin America. When that dried up with the Latin American revolutions the Spaniards were left with little. 1492 in a sense was the beginning of the end for Spain.
That’s strange logic; after 1492 Spain spread its influence through a massive colonial empire throughout the Americans and Caribbean, as well as Africa.
While revisionists will offer their own versions of the story to fit their agendas, Spain’s treatment of Jews at the time was mild compared to other European countries; they offered conversion as an alternative, and that reflected the true purpose: Spain had just recovered its lands from the Muslims (Granada fell in 1492), and the Muslims were still a threat (across the straits in North Africa); they’d oppose them with a unified country, and the faith would be the unifying factor (as various ethnic groups in Spain were unified by little else).
Viewed outside of the military situation, it is easy to portray the Spanish situation as simple hate; it was much more complicated than that. To many Jewish refugees of Nazism, Spain was a refuge; early in the 20th century (prior to Hitler’s rise to power), the Spanish government offered citizenship to the descendants of the Sephardic Jews. To Jewish populations remaining in Arab countries in 1967, Franco offered Spanish citizenship as well (allowing them a way out). Today Spain automatically grants citizenship to the descendants of expelled Jewish people.
I have no horse in this race, being neither Spanish or Jewish.