Aliens built pyramid

I am a proponent of the theory that humans did not build the pyramids. I think the best presentation on this theory is an old video called UFO diaries. The pyramid episode was this series best, giving a half hour of facts why mankind could not have built the pyramids. In UFO headquarters those facts were all repeated. Today, great ancient astronaut experts have given us more reasons to doubt mankind's ingenuity. I want to tell you what seals the deal for me. The hollywood view is that slaves built the pyramid. In fact, Egypt would not have had enough of a population during the scientific dating of the pyramids. Population is what makes me distrust the view that humans built the pyramids. I googled egyptian population in 2500bc. The sites said 20 million. Then I googled 2013. The sites said 80 million. On the same site it said in 1960 the population was 20 million. In 4500 years the population of egypt didn't change. I find that hard to believe. The population of egypt would decline the farther back in time you go. As UFO diaries said, there was not enough people to build the pyramids.