It's probably worth considering that across a sufficiently large distance, they effectively no longer exist. Their signals haven't reached you, and with the increasing speed of the universe's expansion, they will never reach you. Eventually, everything will be expanding at well beyond the speed of light, so short of being able to cut through space and time, we're not reaching any of these destinations. For all intents and purposes, they don't exist for us. We'll never see any evidence, nor could we ever see any evidence.

So in reality, there is a maximum distance we need to consider - the distance where any signal would have any chance of reaching a detectable region.

But besides, this still misses the most important part. Until 10 billion years ago, stars were much too big and poor in metals and unstable. We didn't have an earth until 5 billion years ago. It was inhospitable to life for a LONG time. We've only had multicellular organisms of any kind for 800M years. Our star is unusually calm, meaning we don't have to worry about being bleached every 5 million years or whatever.

I've said this a couple times in this conversation, but the best guess is honestly that we're the forerunners.

I have no doubt that civilizations are out there. Maybe a handful, maybe nearing infinity. But out there.

The problem is "out there" is so far away, we are all isolated on our own island worlds. An ocean of space so vast we cannot meaningfully traverse it with probes or radio, to say nothing of manned interstellar flight.

But it never gets boring for me to imagine what other civilizations there might be, and how they might be different from us and from each other.