Answer:
The main reason was to have access to resources and wealth.
Step-by-step explanation:
After "discovering" the Americas, the Europeans wanted to colonize here, as the new land could be a source of wealth and resources that were scarce in Europe. This indeed happened, the Americas yielded a great deal of wealth to the Europeans.
The potential of US natural resources has significantly altered Europe's economic picture. Old World physical diseases were one of the factors responsible for the decimation of the Native American population. On the other hand, the European conquerors became masters of the lands that were once owned by the Aztec peoples, the Maya and other native peoples, seizing the natural resources and precious metals of those lands.