In most cases spanish explorers and soldiers who came to the new world were motivated by

The Spanish Explorers and soldiers or the Portuguese Empire in the discovery age sailed beyond Europe to America, Africa, Asia, and Oceania to conquer territories and open up trade routes. They were motivated by pursuing riches like gold, silver, desire for power, religious zeal patriotism but never desired to serve their fellow men. They managed to colonize the world from the 16th to the 18th Century where after the return of Columbus from the new world created a series of activities in Europe. The Monarch dispatched armies and explorers to the new continents to establish trade outposts, seek treasures and spread religious beliefs.
Prime areas of the target invasion were the advanced Southern Indian civilizations and Central America due to their gold and silver abundance.