The Qax say hi

almost. What they've found is the one thing the universe lacked. Space Orcs. Well they found us, Not our fault. So let the WAAAGH! Begin. mwuhahahahahahahahahahahahahahahahahaha

Eh, it depends on technology. Oxygen is plentiful in the universe and not that difficult to extract from compounds if energy is available (and for a spacefaring culture, it is). Same goes for almost any mineral resource.

Now, a planet with a complete working biosphere that can be studied and/or settled... THAT is a treasure trove.

lots of carbon dioxide on venus in atmosphere and enough nitrogen (3.5%) to easily extract. Moon titan, absurdly large amounts of nitrogen, methane and water. So places other than earth as sources, though may take more processing to get rid of radioactive isotopes.

comets are full of ice, and may have lots of nitrogen as ammonium salts, no big gravity well to get out of.

Yeah, the old "here to steal the air trope" nope, Realistically there is exactly NOTHING so special on earth that anything would want to steal it. The closest thing I could think/imagine was the original concept for independence day. The earths core.

The answer, unfortunately, is something Gharr probably can't yet express in a human language.

I'm guessing a combination of pride, idealism, and narcissism.

Would he even put it in those terms? Depends on the level of honesty and self deceit he has playing on his personality, and the clear sightedness to cut through through any veils ideology may impose overtop.

Meh, it shouldn't be that hard - why do humans explore the Marianas Trench? *Because they can*.

That's what "true explorers" do. That's what scientists do.

Of course, there are those who do explore for *other* reasons - the question is blunt, distrustful, poorly worded.... but not truly unwarranted.

I dunno what's to question there. They're explorers. They explore.

Were they even aware there was a sentient species on Earth? I mean, before they arrived in-system?

Nope, it was a complete surprise to them. DB has said that they didn't even count the planets before setting out, because Sol was thousands of light-years from any observatory, and it wasn't worth surveying from that far away when they were already planning to come over for a closer look.

It's also worth noting that stumbling upon a sapient world is ridiculous luck (alliance had surveyed something short of a million star systems, found only 15 extant civilizations, so the actual chance of stumbling upon somebody new is roughly 0.000015%). They could easily select Tau Ceti instead of Sol as the jump target, and then not only the plot of the comic wouldn't happen, Earth could remain undetected for further thousands of years.

Edit: It can even be considered pretty much canon fact that there's undiscovered sapient civilizations within the Alliance territory.

And that's something that needs communication. The assumptions earth-side, is it's rare, or so plentiful it's almost a non-event. Humanity doesn't know which extreme to tack to yet. But the fact the technology is within the same epoch is also a surprising realization.