Well, I wouldn't go so far as to call it delusions of grandeur - there are estoteric religious texts and interpretations of dogmatic texts that do support that you are God. In fact, Islamic offshoots (5%) teach that very concept. Satanism and black magic pretty much take that concept and then remove the moral restrictions.
There is a saying in occult circles that the only difference between white (good) and black (bad) magic is the results or intention of the magician.
However, I would not dismiss any of this as delusions; Without hijacking this thread too much I'll leave you with something to consider: Think of the placebo effect in the context of the foregoing discussion. Now consider someone that dedicates considerable practice and time influencing his thoughts and body and you will begin to appreciate our untapped powers. The mind is far more powerful than many of us realize.
As to aliens, that is Hubbard's science fiction background - but the foundation of his story - willing ourselves to existence, etc., very much has its roots in the occult. He was, without a doubt, an occultist.