You are refering to the bacteria in the mojave that metabolize sulfuric acid and an entire ecosystem at the bottom of the gulf of mexico that does the same thing. However, the step from one kind of bacteria to another is microscopic in comparison to the step of matter becoming life. While the universe may be infinitly vast, there is not indication that matter is infitite as well. People often mistake "the universe is infinite" for "matter (and by extension galaxies, planets, and solar systems) is infinite.
Given the unlikelyhood of matter becoming life and the (presumably) finite nature of matter, I don't think it's prideful to consider the possibility that earth is the only planet that sustains life. There is still so much we don't know, and may never know, about how life came to earth.