This is a great debate to partake in. I enjoy debates where noone is really wrong or right, you get so many different ideas and views on things.
First off, I personally do not think any top world leaders or elitists know of other life forms. I feel as if something that big would be leaked instantly, because you know.. We're humans and like to do that shit. However if it turned out that they did know, I definitely wouldn't be surprised.
Do I believe they live among us? Maybe you are some form of intelligent life visiting us from millions of light years away, and just trying to see how good you guys are hiding so far ;p On a more serious note though, once again, I do not believe they do. Although I think that, I still wouldn't be surprised if they turned out to be our nieghbor down the street. Being a human on Earth, I am so accustomed to secrets not being held very well. Which makes me automatically think that if they were here, we would have known by now. Except one thing, they would be from somewhere far away (or not so far away maybe) and may be able to hold such secrets from us.
As for help from intelligent life.. I feel as if they are so intelligent, they will/would just observe us. To see our methods of doing things. Here is something to think about though, The Fermi Paradox. If you're not familiar with this, it's basically the question "Where is everybody?". I'm not going in full detail (I will leave a video and another link to read up on if you wish). I DO believe there is other life forms out there. Whether it be just some form of plants, or any living organism for that matter, not necessarily any super life forms. HOWEVER! The Fermi Paradox brings up a VERY good point. If they are so advanced in technology, we would have seen them, or atleast have had an encounter with them by now. I
Highly suggest reading the article and watch the video I post on the Fermi Paradox if you're into this type of thing.
Fermi Paradox Video:
https://www.youtube.com/watch?v=sNhhvQGsMEc
Fermi Paradox Article:
http://waitbutwhy.com/2014/05/fermi-paradox.html
Now for the pyramids...
I never really believed aliens helped us with the building of these. Why do I say this? I feel that if we had help from another foreign civilization (with their technology we assume they have) the pyramids would have been MUCH greater and grand. Don't get me wrong, the pyramids are AMAZING, structurally and beauty. However, they are very simplistic. I recently have came across a video on a new proposed theory on how the pyramids were made and honestly, I feel like this is spot on. I suggest watching this 21 minute video, it's very interesting!
Building of the Pyramids:
https://www.youtube.com/watch?v=C1y8N0ePuF8
I really hope to hear from everyone else and their views on this!