Do you believe that there will ever be an alien invasion?
no. only in science fiction stories and movies lol 
amazing, since you are quite knowledgeable, how do we define an alien invasion? 
it's simply aliens invade the Earth either to exterminate human life or harvest people for food, steal the planet's resourses
When did this word ever come into play? have there been any sightings? or it's just a figment of someone's imagination
Alien invasion was a common metaphor in US science fiction during the Cold War
Do you think Hollywood might have blown the whole idea of alien invasion out of proportion?
I don't think so. i think a lot of people like the idea of aliens contacting Earth and observing it either to invade or sometimes help humans