If we could come up with this idea, why couldn’t extraterrestrials? What if, if they do exist, they are just observing us and sightings are accidents? Aliens are usually viewed as wanting to dominate or annihilate Humans. Well…if they have the technology to do so, why haven’t they if they’re already here? I think domination and annihilation are unlikely motives. That doesn’t mean they have good intentions either, but that also doesn’t mean they have bad intentions.
Since there are different species, there are probably different factions too. Maybe some of them are all for revealing themselves but they are being prevented from doing so. Many times its shown that when aliens reveal themselves in the media, Humanity unifies and rises against them with military force. What if the opposite occurs? What if it causes such chaos we go against each other? There could be good reasons why they are going about things as they are.
We could be a zoo, and while we think we are above all other animals, perhaps ET view us as nothing other than an Earth animal. We could be an experiment and they don’t want us to know we are lab mice. But we’re catching on. As we continue to develop, they might feel a need to intervene. We may be an experiment that has gone really very wrong!