Many people believe that the existence of alien visitors is being actively suppressed by world governments, or even by a cartel of highly placed none governmental entities. I do not want to address whether this is true or not, as that horse has been beat to death. But instead I want to address the reasons for this suppression, if it exists.
The usual argument against revealing the existence of alien visitors is the likelihood of social and religious upheaval that would occur subsequent to such a revelation. I would counter such a suggestion with the fact that, according to National Geographic survey, over one half of Americans believe that there is life on other worlds, and as many as one third of Americans believe we have already been visited, surveys conducted in the UK had similar results. With numbers like that it is hard to accept the mass panic scenario. And when considering that the above American statistics are coming from a country that is over three fourths Christian, it is highly likely that a significant number of Christians already accept the existence of alien life. The likelihood of a major religious crisis as overblown as the likelihood of a mass panic.
So what reason is left? Greed… Pure and simple, as old as money itself, “Filthy Lucre”.
What is the logic that leads to such a motive for preventing disclosure?
The world economy revolves around fossil fuels oil, coal, natural gas, and the emerging technology of methane hydrate. Yes we have nuclear wind and solar, but their total contribution is small. Overall, energy is between 8 and 25% , depending on sources, of the world economy.
Then there is the one inescapable fact. The distances involved in interstellar travel make it absolutely impossible to travel from one star system to another in any conceivably practical time span using any type of power source humans have ever conceived of, including nuclear. Therefore, any aliens visiting us would be using a power source far beyond anything we have conceived of. Such a power source by definition would have to be small reliable and would seem to violate our current understandings of physics.
The confirmed existence of alien visitors would, by direct implication, also confirm the existence of such a power source. This fact would no doubt be overlooked by the majority of the world’s population. But there is a significant number of people who have enough of a understating of physics that they would recognize the energy implications of catapulting a ship across stellar distances. Their curiosity would be piqued. Once the possibility of such technology is proven by the existence of interstellar travelers it would only be a matter of time until humans acquire the same technology. Humans can be incredibly determined, sooner or later, either by deduction, subterfuge or even outright theft, someone would duplicate the technology. I have not done the math but based the size of commonly sighted UFO’s and the recent math equations around the energy requirements for a Alcubierre drive, I would feel completely comfortable saying a human derived version of such alien power technology could possibly result in a device the size of a newspaper rack that could provide the total energy supplies of a standard residential single family home for centuries. Once such technology was developed the world economy would be turned on its head overnight. Many of the worlds rich and powerful would no longer be rich and powerful.
When considering this, I highly doubt that we will ever have disclosure in my lifetime.