Do you realize that most native Americans were killed by European disease decades or centuries before a European ever showed up to their area? And since no one even understood the concept of disease or how it was spread, it was really hard to imagine the Spanish purposefully showing up in Mexico with the explicit purpose of killing people in S. America via smallpox.

And paying someone a high salary to do a job they can leave at any time, isn't causing them to sacrifice their life, it's called free trade is generally considered 'winning'.