Until they actually have evidence for life on other planets, there's 0 reason for me to believe there is.
All they really have is "what if there's life on other planets." I don't chase around what ifs. What ifs are not evidence, what ifs are not reality, what ifs are just doubt, and I've found that doubt on its own is very weak. You can sit around and throw what ifs at anything, but the what ifs are ultimately meaningless if they have nothing to accompany them. What if Jesus didn't raise from the dead, what if the Muslims are right, what if the Mormons are right, what if Obama wasn't the president, etc. These statements are meaningless and to me, there's no point in considering them because all it is is a what if.