The correct answer to this open question is the following.
King Ferdinand of Spain and Bartolomé de las Casas used to impose the Encomienda system on the premise that conquered land belonged to the Spanish crown, under the service of God. King Ferdinand knew about the many raw materials and natural resources from the Americas and was urged to exploit those resources to the benefit of Spain. Bartolomé de las Casas owned many Encomiendas on the island of Cuba. So he was not only interested in evangelization and on the conversion of American Indians into Catholicism, he loved getting rich and that's what he did through the Encomienda system. The Encomienda system granted subjects to work and exploit the land and control the Indians who paid tribute to the Spanish monarchy. A very unjust system of exploitation.