I wondered about this in 8th grade without knowing of Chariot of the Gods.
After years of fascination with outer space, I started to wonder why Mars looked like a planet that had undergone devastation. Rubble, and no visual trace of water despite ther being polar ice caps! It seemed to me this planet may have been inhabitable at one time. The fact that Mars is known as the god of war also led me to believe that some kind of war may have been responsible for the destruction of Mars.
I continued to wonder what type of beings would have lived there. Being us whites burn in the sun here on earth and darker folks don't, it was obvious a lighter toned race would have lived there. I then wondered if it was possible the white race, which only inhabited the Eurasian continent at one time, may have settled there after an exodus from mars.
It's also made sense to me that since Mars was further from the sun and this colder, the comforts of the warm sun and ample vegetation enjoyed by the natives of earth, would have been less. Summers would have been shorter as well as the agricultural season, and winters longer. These stimuli would have pushed the Martian brain to find more advanced means of survival beyond those here on Earth. Hence, why white Europeans, in general, were most advanced technologically over other regions of earth. This, in conjunction with their history, may very well explain the reason for their need to conquer other regions of earth and introduce their "modern" advances to the natives who never had a need for them.
I also had theories as to why the super advanced technology that led them here didn't remain in their culture. Perhaps a lack of immediate resources or means to aquire them led to some developments being lost or forgotten generation after generation. As they multiplied, the history may have been held by a few yet forgotten by others not so tight in the ruling circle. Despite forgotten skills, the Martian brain was still advanced in problem solving and resulted in the development of advanced means of survival especially in colder regions.
Then began the questions of Egyptians, Mayans, Etc.
Well, years later, a HS history teacher introduced me to the book Chariot of the Gods after hearing my theories. This book made me see there was some logic to my logic and presents an excellent case. It has, to some degree, answered some questions I've had, questions that truly have no definitive answer, FOR TRULY WE CAN ONLY THEORIZE, these ideas are not concrete fact.
Watch a show called Ancient Aliens. It's great fun to wonder about the unknown.