I have my doubts we are living in a black hole also.I do not believe this is truely the case as well. I envision a point of quantum pudding in which all matter transitions to its primordial state: energy.
I just have this nagging thought of the expanding universe with reference to "where is all this space coming from?"
Could be living in just the expansion phase of one though.
Everything from nothing is a good reason for everything or E as you correctly put it.
Could be as simple as nothing had potential energy or was unstable and that is the reason for quantum fluctuation.
Fluctuation E balance can do the rest to build the rest.
Nature hates nothing.
Expansion into fluctuation that was originally nothing.
Expansion just an over energy or feedback loop of a region.
More E than allowed in a region or collision of another region.
Then nature has a clear logical step plan to go from nothing to everything we see and more of the same happening everywhere in forever.