The decision to visit planets other than Earth is not supported by everyone. What would be a good argument against sending humans to other planets?

Many people favor the idea of visiting other planets. However, there are those who believe that this might not be a good idea.

An argument against sending humans to other planets is the fact that we are not usually good at taking care of our own. Therefore, if we reached other planets, there is a risk that we would be equally destructive and damaging. Even if we had good intentions, sometimes this damage is done without us being aware of the mechanisms behind it. An example of this is the way in which Spanish explorers spread unknown diseases in America after their discovery of the continent.