I’m sure it hasn’t happened more than a handful of time, but Stephen Hawking, arguably one of the greatest minds to ever grace this Earth, is wrong. He is wrong when he says that the human civilization should actively avoid contact with an alien race. He is wrong when he states that they would want to exploit our Earth for its natural resources. The simple truth is that we should try to make contact, the question is if we were heard would they make contact with us.
Invasions from another world makes for great science fiction movies in Hollywood, and even though nobody on Earth has ever met an alien being eye-to-eye we can rest assured that if we did it would be one explorer and curios mind meeting and saying hello to another. How could we be so sure? Think about it. If raw materials and energy is what would drive an alien race to venture out amongst the stars for new lands and territories to conquer, then building materials and energy would be the first issues they would have to solve in order to traverse the gulf that expands out in between star systems, but first in order to do that they would have to find sources of energy that they could derive from interstellar space (because conventional fuels simply would not do; you can’t carry enough with you to make the journey) and you would have to build ships with skin that could virtually last forever in order to withstand the constant bombardment from interstellar radiation and/or debris.
Once you have done those two things figured out why would your need to rape a planet and alien culture of their precious resources when you have solved pretty much all of your problems in your need to cross the vastness of space in the first place?
Any alien civilization that would strive to build ships and even devote the time to travel to another planetary system would therefore do it for no other reason that they would want to reach out.
The real question is would they even want to do that? Would they want to reach out and make contact with a civilization like ours? The cruel reality of our little blue dot in the ocean of space is that we have yet to learn to quench our energy needs in a way that not only doesn’t destroy ourselves, but also is derived from a renewable energy source that makes our needs less confrontational. If anything they would stay away from us for the same reasons that Stephen Hawking said that we should stay away from them: because we would want what they have.