Excellent thread. Numbers aside, it's hard to believe that we are the only life in the universe. The idea is absurd if one really considers the number
of stars, even assuming life must look more or less like us.
"Why would they bother visiting us" is an important question.
I think perhaps for a civilization to develop advanced technology, certain ingredients are needed.
For example the ability to manipulate tools. Fine motor control. Not just the ability to bang a stick on something, but the fine control needed for
carving, building, etc.
While many such ingredients are obvious, some are not. Curiosity for example. Sometimes its a bad thing: what happens if I stick my fingers in that
electrical outlet? But as a species, our curiosity is insatiable. What's on the other side of that mountain? Why does that bear not eat it's prey
right away? What happens if I try to mix oil and water? As soon as we have the answer we search for the next puzzle to solve.
We spend significant time and resources on pure research with no specific goal. It is far from optimal. But it's hard wired. It's just what we do.
What possible gain from studying the migration of monarch butterflies? It doesn't help us grow food or colonize planets, yet many people spend their
lives on such things.
So what if a species needs this sort of drive to advance tech? Otherwise, as soon as they figured out how to get basic needs, they would go no
further. They would sit back, get fat until the next extinction hit. But they would never develop rockets.
If this is the case, then every species with tech out there would investigate others, because that is what they do. It's hard wired.
A completely different angle, if you were alone on an island you would seek others. Even if you only found a squirrel that didn't even notice you, or
a dog or whatever, no one wants to be alone. If a species is their own master, the universe becomes a vast and lonely place.
Anyway, just some thoughts. Hope it made sense