I would venture to say that most scientists, and anyone who knows something about science, would accept the premise, that the life we know of, that started on Earth, (abiogenesis) and then evolved over the eons, to what we see today, would not be the only life that has started and evolved in this rather large near infinite universe, of near infinite content. Most I believe would accept the likelyhood that Earth is not "Robinson Crusoe" in that regard, while still understanding that as yet, we have absolutely no evidence of any Alien life form ever visiting Earth, if any other Alien life form does exist. Abiding by the laws of physics, the two great barriers preventing any Alien inter-species contact, are time and distance.
Of course as yet scientists cannot be sure that life at some degree of evolution does not exist, closer to home. eg: Beneath the ice-covered moon of Europa, or the apparent hydrothermal activity on Enceledus, moon of Saturn.
Also as I mentioned somewhere sometime on this forum, I have seen what can be regarded as a UFO or if you like, a UAP. That sighting many decades ago, does not, nor ever has caused me any concern. It simply remains unidentified or unknown.
I don't accept that believing in Aliens, would be anything to be too concerned or worried about, or that it is in anyway dangerous. As long as that belief is accompanied by the fact that we still have no evidence of any other life form off this fart arse little blue orb we call Earth.