Humans who see others receive praise and awards for good grades in school cheat on their exams even at risk of discovery and punishment in order to step into the spotlight. Police files show that copycat crimes occur because the perpetrator desires the spotlight, and those walking into the police station to confess are almost invariably not a criminal but simply an attention getter. The desire to be the center of attention frequently overrides fear of punishment or derision. The desire to be the center of attention is strong, and where it cannot be satisfied otherwise can drive a human to present false claims. Thus where UFO research groups interview contactees and occasionally publish their stories, it is inevitable, in human society, that false claims of being a contactee would be made.
False sightings are another such claim, as are claims of alien identity.
UFO research groups have long held back key data files from their publications, by agreement, so that false contactee stories could be identified. The public, however, doesn't have access to the transcripts, nor are they privy to the patterns the mass of data forms. The public can be fooled. False claimants have enough information at their disposal to put together a credible story, claiming contactee status or a sighting. Where the false claim includes alien identity, it is easily discredited, as no alien life forms exactly equate to the human shape and DNA composition.