Stephen Hawking, the man who proved the existence of black holes (the guy in the wheelchair, if you don't care), stated that aliens will kill us and ruin the human race. Personally, I find this to be completely false.
1. Aliens that are advanced enough to travel to our planet in spaceships would have a vast knowledge in a variety of disciplines. They would have no need for any 'advanced technologies' that we may have, unless they have evolved differently and created different technologies.
2. They would not come to Earth just for our resources, when they could go to other bodies without the hassles of dangerous bio-hazards(us). By coming here, there would be the danger of mining amid fatal diseases that they have never come in contact with. Also, there are other bodies all over space.
3. Finally, if they had the knowledge and technology to come to Earth, then they would probably be smart enough to think ahead and be safe, by not spreading/contacting our biosphere and wearing hazmat-like outfits. No one would take the risk of coming into contact with strange diseases of an alien world.
Do you agree with me, or how do you disagree?