Note the difference in terms here.
JGirl mentions the lack of any evidence, while LRW mentions the lack of "proof."
Is evidence proof?
Of course not.
There exists evidence for everything the mainstream theorizes on. There exists no evidence, on the other hand, for alien inrtervention.
Yet a person that decries the fact that Egyptology can't "prove" their theories happily gloms onto an idea that doesn't even have one iota of evidence behind it, much less "proof."