I recognize that the universe is so vast that it's likely that life forms other than us exist in it, but that's the extent of it.

I've seen no verifiable evidence that they in fact do, so I don't "believe" that they do.

Really, I don't "believe" in much of anything for which there is no verifiable evidence. I don't even understand how that works - how it is that other people apparently do. It's not a conscious choice or anything - it's just appears that there's a set of requirements that must be met before the position of "belief" is triggered inside my mind, and one of those requirements is verifiable evidence. Without that, the state of "believing" just isn't triggered, and it's not as if I can somehow force it, so that's that.

As far as I can see, governments are comprised almost entirely of psychopaths, opportunists, charlatans and fools, so I see little likelihood that they possess concealed knowledge regarding any nominal extraterrestrial life. First, and most simply, if they did possess any such knowledge, it's near certain that somebody would've blabbed something by now.

Beyond that though, I think it's exceedingly unlikely that any alien life form capable of traveling interstellar distances would, on arriving on the Earth, seek out contact with a government, much less limit its contact to a government. If they're that advanced, it can only be the case that they, in their own development, either never bought into the flatly ludicrous and clearly destructive idea of institutionalized authority or overcame it before it inevitably destroyed them, and in either case, I don't see any reason why they would lend any credence to our mass delusion that this one subset of humanity forms a specially qualified and empowered elite that rightly oversees everyone else's interests. That's our delusion - not theirs.