Not finding any life anywhere (although hard to take samples outside the solar system) could maybe be even worse. That’d mean that it might be that some stronger version of the Anthropic Principle holds, and it could be that we’re completely alone in the universe because it’s sort of “tuned” to us, although without the intentionality that implies; random shit just happened until an incredible collection of very unlikely coincidences produced us, and just us.

Whether we find simple life out there or not, I’m honestly pretty convinced that what’s going on right now is at least our filter, and possibly the Great Filter. A species’ ability to transform its environment might always outpace its understanding of what the outcomes will be, and getting to this point might possibly also require a competetive species, so it might just be near-inevitable that technologically advanced species kick off something like a “terminal” climate disaster or nuclear war eventually.

Add to that the fact that it’s not at all sure that space colonization is actually doable, at least in a time frame that would allow species to spread to other planets before they screw the pooch with their original one. Not only is space travel ridiculously hard and has a ton of terrible health effects which for us humans include eg. blindness in prolonged zero-G (even a trip to Mars would be enough to badly fuck eyesight), it also takes stupid amount of resources since you have to build spinning habitats for your ships, stations etc to solve at least some of the problems and you’re probably already running out of resources on your home planet. Building a self-sufficient colony on another planet is another thing that many researchers think is likely so hard that it may as well be impossible at least for the next few hundred years, and we probably don’t have that long – whether it’s us triggering some “black swan” event and doing a speedrun to turn Earth to Venus, or climate change just getting bad enough that billions die and in the resulting chaos we pretty much nuke the rest, or whatever. Looks like we’ve been just smart enough to fuck things up, but so far just not smart enough to un-fuck them.

So, if we find no signs of any life and we manage to effectively destroy ourselves somehow, the worst case could be that that might be it for the observable universe’s or even the entire universe’s life. Finding unicellular life would at least mean that it’s possible something else pops up somewhere at some point, but we’d be just as screwed as we would be without that discovery.