Let’s take a rational look:
Right now lifting one pound into low Earth orbit is very expensive. Much more expensive, by far, than shipping one pound around the world in the 1500s. Once in low Earth orbit (LEO), it takes relatively little expense in fuel to boost that pound anywhere in the Solar System. it doesn’t take much to boost it to the nearest star, either, if you don’t mind waiting millennia for the cargo to arrive. If you want it to arrive within 4.5 years, which menas boosting it instantly to 99.999999% of light speed, and then decelarating it instantly at the other end, you’re talking about a major expense again.
Therefore interplanetary piracy, never mind interstellar, is worth a great deal more many times over than the plunder.
Of course we don’t know all there is to know, but we’re not ignorant, etiher. We know how to lower launch costs to a small fraction of what theya re today, at the expense of large capital invesmtents. It would be possible, using space elevators, mining the asteroids, the moon and other planets int he system, using solar sails, electromagnetic tracks, and other things, to launch an interstellar ship at aabout 1/3 light speed to anywhere in the universe you care to aim it. At such speeds a ship would take over 13 years to reach the nearest star. So any invading aliens in Proxima Centauri would be better off developng industry on their own.
I’d worry about real estate. Earth is an atypical planet compared to the rest of the Solar System and an outright freak of nature compared to what we kno fo extrasolar planets. Any aliens from an Earthlike world looking for new lands to inhabit might invade and conquer Earth, and perhaps wipe us out, just to own the land we now ocuppy.
as for hypersace, antigravity, and other double-talk drives (with apologies to Larry Niven), they make a good story, but we’re as likely to have them in real life as we are to find unicorn feathers (yes, I’m aware of what I just said).