(I'm sure you know this, but just to be clear, "self-delusion and fraud" is a fully general counterargument/explanation, and you likely wouldn't be motivated to use that counterargument/explanation unless you thought psi was unlikely for other unmentioned reasons.)
[Post redacted 'cuz I unfairly and carelessly misrepresented someone's views (Eliezer's). The messages of this post was: disbelief that aliens visit Earth in spaceships is a bad reason not to look into ufology. My apologies for this ugly post.]