I have no expertise in the matter, but largely agree "realization" should be when "value is assessed and used for gain" and not a strict sale. That being said, I don't want the Pandora's box of redefining "realization" opened.
You can do it carefully and one clear scenario at a time. First, go with collaterization. Then, when billionaires find something else, go with that. And on and on.
