Healthy skepticism will not win friends and influence people. :)
Nor will flatly accusing thousands of military personnel, air traffic controllers, astronauts, professionals, blue-collar workers, farmers, regular Joes, moms, dads, pilots, and policemen who claim to have seen these things of being either ridiculously dense and delusional or else bold-faced liars.
Although mysterio's cute habit of referring to aliens as "space monsters" is endearing! He is safe in the knowledge that all that mean, bad stuff he read and saw as a kid in'50s SciFi was make believe. The sad part is that he extends that to mean that thousands of people from all walks of life (including my husband and my Marine step-son) will tell ridiculous lies just to try to frighten him -- and also that our nice, transparent military and government wouldn't go to great lengths to hide, obfuscate, and deny any official knowledge of what would plainly be the biggest threat to national (not to mention global) security of anything yet known to man. No -- they'd never do that ....!!!
There's a "delusional" part that plays a role here, for sure, but IMO it belongs to a whole 'nother set of people ... I ain't mentioning any names, but their initials is mysterio and JoJo Gunn! ;^)