[user104658]

I think it's safe to say that there are countless planets in this galaxy alone that are host to life as intelligent / more intelligent (and more advanced) than we are... however, I personally don't believe that aliens have or ever will visit Earth (nor will humans visit worlds with intelligent alien life), because I strongly suspect that FTL (faster than light) travel is physically impossible. So all of these intelligent lifeforms will be confined to their own little corners of the galaxy, never having contact with any of the others... well, except those who are lucky (or unlucky I guess?) enough to have an alien neighbour "next door", within the same solar system or in the systems of the closest stars that would be possible to reach fairly easily at sub-light speeds.

Anyway... HYPOTHETICALLY they would probably be better to keep it from most people. Most people don't even like to face the uncomfortable truths of the world as it is outside their own little bubble (family, work, friends). Most people don't even "want to know" when it comes to domestic politics... certainly not global concerns... so, they definitely would prefer to stick their heads in the sand when it comes to extraterrestrial matters.

Then again, considering that, they might as well make the information easily "findable". THen those who want to know will know, and those who don't want to know will go on in ignorant bliss / pretending that it isn't happening... as they do with anything else that doesn't "fit" in their comfortable mindset.