I”ll believe in space creatures when someone comes in with one strapped to their hood.
In my mind the most credible evidence of such stuff is not the many distant flickering lights but anecdotal accounts of people who believe they have been abducted.
There is a substantial body of such and it has been collected and analyzed by credible people (people like John Mack, now deceased Harvard psychiatrist, and Budd Hopkins).
The abduction accounts paint much too consistent a story (a very complex and powerful story BTW) to be fabricated.
Since these stories are anecdotal in nature and provide only circumstantial evidence, it is fair to question whether or not they might be some kind of mass hallucination.
That said, those who have studied and written about them find them perplexing. Hallucination or not, the stories are vast in number and all are consistent down to the tiniest details. And the abductees report having been abducted over their entire lifetimes, indeed over several generations within the same family.
And those who have been abducted have been deeply traumatized and emotionally scarred by the experiences in much the same way as sexually abused children have (in fact, John Mack at first thought the abduction stories might be metaphorical covers for such abuse--he later dropped that idea).
Long story, short, those who have studied the abduction accounts all come to some pretty profound conclusions.
They have concluded that the abductions are, in some manner, real and that they are caused or created by some beings of an extradimensional nature and not extra-terrestrial.
Also, they have concluded that these beings, whatever they are, do not have our (human) best interests at heart and cannot be trusted or believed as to what they say or how they portray themselves. It has been concluded that the abductions, whatever their goals, include the systematic rape and physical and mental abuse of the victims.