10 Reasons Aliens Won't Invade Earth...
I tend to think that #3 is number one but the rest have merit.
 gearl
                                                
                                                Level 8
                                                Feb 11, 2018
                                            
                                                
                                                    gearl
                                                
                                                Level 8
                                                Feb 11, 2018                                            
                                        Very true.
My train of thought on that one is that if a species has the ability to travel light-years.  And maybe even travel at the speed of light, by comparison to that kind of technology... I'm sure they would still consider us to be a primitive speices. 
This is great. The only reason I could think that a alien would come here is to get a good beer, but that assumed that they could drink it. They probably could not. We are quite violent, though they could kill all of us without a thought from us, why chance it?
 dalefvictor
                                                
                                                Level 8
                                                Feb 11, 2018
                                            
                                                
                                                    dalefvictor
                                                
                                                Level 8
                                                Feb 11, 2018                                            
                                        I think the main reason is that they're just too damn far away and, like us, haven't yet developed the technology to traverse these distances.
 MrControversy
                                                
                                                Level 7
                                                Feb 11, 2018
                                            
                                                
                                                    MrControversy
                                                
                                                Level 7
                                                Feb 11, 2018