Extraterrestrials 100% exist and we 100% have been visited and are probably being observed right now. However, in our current state it wouldn’t be wise for them to reveal themselves and offer us advanced technology and the such, and they know this. You only need to look at how we treat other people, let alone beings from other planets. And fantastic films such as Arrival (2016) do a good job at illustrating how even good intentioned beings would cause mass panic and hysteria. And when you couple that with feeling vulnerable due to their technological and social superiority then you have a perfect storm that would likely be hugely detrimental to ourselves. And you’d also have the danger that many would begin to worship these beings as gods, which would be wey disempowering for us and so I think all of these reasons and more are why super advanced otherworldly beings choose to remain unseen from us until we’ve evolved to the point where we can interact with them maturely and constructively. For them it must be like adult scholars watching a bunch of unruly toddlers. Even just their very existence would have cataclysmic effects for most of the world’s societies that are ruled by Abrahamic religions. Suddenly beings from other planets who obviously don’t have the same religions, prophets, myths and so on…that would shatter the God delusion and our place in the universe for so many. No way, we’ve got a long way to go before advanced beings make open contact with us.