What is the reason to believe in the existence of extraterrestrial life?

There are several reasons to believe in the existence of extraterrestrial life. One reason is the vastness of the universe, with billions of galaxies and planets that could potentially support life. Additionally, the discovery of extremophiles on Earth, organisms that can survive in extreme conditions, suggests that life could exist in harsh environments elsewhere in the universe. Finally, ongoing scientific research, such as the discovery of exoplanets in the habitable zone of their stars, provides further evidence that extraterrestrial life may exist.