One of the main scepticisms with people who say they've witnessed alien crafts or had direct contact with alien beings is that they do not seem to have hard, irrefutable proof.
In an age where a majority of the world population has smartphones capable of taking decent to high-quality photos, it seems odd that despite multiple alleged sightings of UFOs, there just isn't a clear photo or video that simply cannot be dismissed as fake or inconclusive.
Granted, there might be some level of government coverups involved as well if they think this shouldn't be made public just yet, but even then there must be at least a handful of photos.
Also, there have been countless proofs of UFOs having crashed and there isn't a single piece of extraterrestrial material or piece of technology. That could change however if a prominent UFO research group's claims are proven right.
A UFO research group called To The Stars Academy of Arts & Science has recently hinted that they might have obtained exotic extraterrestrial samples from UFOs. This came after a recent Q&A with The New York Times.
It was this very group that had also procured three UFO videos that the US Navy admitted to being legitimate. Of course, just because the videos are legitimate doesn't mean that the videos show actual alien spaceships, but this does give the group some credibility.
Right now, they are trying to conduct different sets of analyses on the UFO samples which will include physical analysis, molecular and chemical analysis and also nuclear analysis.
It seems like they don't want to leave any stone unturned to prove that the sample they have actually came from an alien race. If this is proven conclusively, it might shake the scientific community to the core as this would prove that some other life form exists out there.