What motivated the Spanish to conquer and colonize the Americas?

Why did the Spanish conquer and colonize the Americas? Young students are typically taught that "Gold, Glory, and God" led to the Spanish empire. But the real answer is probably more complex than that.
A prerequisite for Spanish exploration was the Renaissance. The Renaissance brought Europe out of the Middle Ages and into the modern era. Intellectual pursuits, including the study of geography, were valued. The Renaissance inculcated the Spanish with a curiosity of distant places. The Chinese, on the other hand, chose to eschew voyages of exploration as the Spanish made rapid strides.
Another factor that enabled Spain to establish an empire was its national unity. The Spanish kingdoms of Castile and Aragon were united in 1469. In 1492, the last Muslims on the Iberian Peninsula were subjugated. Because foreign voyages of exploration were so expensive, only a united kingdom could undertake them. By the end of the fifteenth century, a unified Spain was ready.
Trade was an extremely important motivation. East Asian trade had become valuable, and spices from that region were coveted by Europeans. Portugal and Spain sought sea routes to east Asia because overland trails were dominated by hostile Muslims. While Portugal gradually sailed around Africa, Spain decided to reach the East by going West; Christopher Columbus tried to reach Asia by sailing West.
The Spanish reached the Americas, not Asia. It took them years to realize this. In the meantime, they conquered the Aztec and Inca empires and stole huge amounts of gold and silver from the Indians. They killed, enslaved, or converted the Native Americans and built an empire which lasted for centuries.

Spain had three major motivations to conquer and colonize the New World of the Americas. These included the accumulation of wealth, winning the competition with other European powers for global dominance, and the conversion of Native Americans to Christianity.
By the late 15th century, it had become extremely difficult to travel overland to the lands of the East for lucrative trade. The Silk Road had become arduous and dangerous, with plentiful robbers and middlemen demanding taxes. The water route involved a long journey sailing south around southern Africa. Christopher Columbus proposed sailing due west to reach the lands of the East, shortening the distance and expense of the journey. Once the Spanish royalty realized that Columbus had set foot on entirely new lands, they sent mercenaries known as conquistadors who ruthlessly searched for and appropriated gold and other precious substances.
At this same time, Spain was in competition, especially with Portugal, to colonize newly discovered lands. The Portuguese empire spread to western Africa, western India, and eventually Brazil and some of the islands of the Caribbean. Spain, in turn, hastened to explore and colonize the Americas to claim as much territory as it could for its own empire.
The Spanish Crown was intensely interested in converting Native American populations to Catholicism and sent priests to the New World along with the conquistadors and colonists. However, native populations were usually subjugated and often enslaved. Although these priests witnessed and reported these atrocities, little was done to stop them. One priest in particular, Bartolome de Las Casas, wrote extensively about the treatment of Native Americans in the New World and criticized the encomienda system, which bound Native Americans to certain landowners. His protests and those of others had little effect in alleviating the misery of Native Americans oppressed by their Spanish conquerors.
http://www.bbc.co.uk/history/british/tudors/conquistadors_01.shtml

https://www.history.com/topics/exploration/christopher-columbus

https://www.legendsofamerica.com/spanish-explore/

The Spanish conquistadors were primarily motivated by three factors commonly referred to as the "3 G's." The three G's were gold, God, and glory.
First, we examine gold. The Spanish hoped that through conquest of the Americas they would greatly expand their wealth. Wealth through acquisition of gold would not only signify power to other European powers of the time (England, France, Portugal, etc.), but it would also serve to further strengthen Spain by providing them with the financial resources necessary to build up their military and fund future colonization ventures.
The second "G" would be God. The Spanish, and the other European powers of the time, felt it was necessary to spread Christianity to those who did not practice it. They believed that Christianity was a trait of civilized society. Their ethnocentric views regarding religion led them to believe that the natives in the Americas were not a complex and developed civilization, but rather a savage society in need of saving. The belief existed among the Spanish that it was a duty of theirs to convert the natives to Christianity. Conquering and converting the natives to Christianity was a central factor in encouraging Spanish conquest of the Americas, and in a way, it provided justification to them for everything that they would do in the process.
The last "G" is glory. At the time of Spanish conquest it was a desire of many men to be heroic military leaders. Military success could lead to rewards from the Spanish royalty and could lead to a greater status in society. By conquering the Americas, many of the Spanish conquistadors hoped that they would be rewarded and would be remembered as great warriors and heroes.
When looking at the motivations for the Spanish to conquer the Americas we notice that many of their motivations are similar to motivations of individuals and groups today. People today often undertake certain tasks or jobs for wealth (gold), religious or spiritual reasons (God), or fame/status (glory). It is interesting to make this comparison and realize that many of our motivations today are not far removed from those of the Spanish conquistadors of the 1500s.