I’m not the poster you’re asking this of, but the reasons why a seemingly empty universe are concerning basically all boil down to “it indicates that the universe is hostile to civilization specifically, or to life in general.”

If the universe is neutral or friendly to civilizations, then we should expect to find someone out there in fairly short order. The universe is so large, even if there’s only a one in several billion chance of a particular solar system birthing a civilization, there should be a few others besides us already in the Milky Way.

If there’s not anyone else, the best case is that we are simply the first (this is my personal bet). Worse scenarios include civilizations simply fail and die after some time, or that one “predator” civilization kills off any other civilizations it finds before they can become a threat.