“I just don’t see the economic benefit in raiding Earth for mineral wealth.”
Maybe they don’t need minerals but they need slaves. Or maybe they just need a place to crash during their intergalactic journeys... It’s a little hard to predict what would be in the mind of someone born and raised at the center of a star. Hawking is probably correct though that humans shouldn’t assume that we’d want them over for dinner.
One thing I think that we have learned here in the US is that machines are cheaper than slaves (I at least have learned that machines are a whole lot easier to keep working than people).
Or maybe they'll need to make room for an Interstellar Bypass... :)