Why are aliens here?. There is no certain answer to this question. But, there are lots of possible reasons. As it stands we only have the faintest idea about some of their activities while they are here. They have been seen shining strange lights at the ground as they fly along, apparently scanning as if they were searching for something. They have evidently abducted many humans and are still doing so today.
The latter reason leads me to believe that their reasons for being on Earth are scientific, at least in many cases. But, there are many different races from many different parts of space and it is very likely that they each want to do their own research. Even on Earth one country or even one scientist will not rely on the research of another and will do their own work to confirm the findings of others. Given the possible number of alien races in the universe, we could be getting these scientific visits for some time.
It is also possible that we are a novelty. We do not know if there are any others just like us in existence. If we are in some way different from the other forms of intelligent (I am assuming that we are seen that way) life in the universe, it may be that we have become a tourist attraction. This would also explain some of the sightings where there seems to be very little happening. Some tour guide forgot to turn on the cloak and the tour “bus” was visible when it should not have been. Or some alien kid was out in his dads space “car” and was raising hell, just like some young humans do when they are given half a chance.
It is highly unlikely that they are here to eat us because if they were, we could do very little about it considering their advanced technology and we would be treated very differently. There would be far fewer humans on this planet.
However, I am not totally convinced that they are all completely friendly and benevolent either. Simply because whenever there is a UFO spotted anywhere and it gets back to the airforce within a short time there are black, unmarked helicopters racing to the scene. Why? It can only be for one reason. To police them. So the if American Air Force think that there is need for military action when one is sighted, that is certainly a cause for concern at least.
This is for two reasons. First the aliens may have displayed aggressive tenancies before necessitating the armed response. Or second, there is absolutely no need for the armed response at all and the military are causing trouble where none exists. So, which is it? I don’t know myself. If you do, I would love to hear from you.