Unfathomably? Oh, come on. It must be at least possible to fathom it!
The OED tells us that to fathom means "To encircle with extended arms." So: Can you get your arms around it? Can the government get its arms around you?
The opening ceremony also had a giant production number celebrating the National Health Service, replete with hundreds of dancing doctors and nurses in period costumes, and children in pjs bouncing on oversized hospital beds.
Socialized medicine will encircle you with its extended arms.
J.K. Rowling (the "Harry Potter" author) read from J.M. Barrie's "Peter Pan" — video — and we were told that Barrie donated the royalties from "Peter Pan" to GOSH (the Great Ormand Street Hospital). We saw "GOSH" in big lights along with "NHS" in that production number.
(Wikipedia: "When the copyright originally expired at the end of 1987, 50 years after Barrie's death, the UK government granted the hospital a perpetual right to collect royalties for public performances, commercial publication, or other communications to the public of the work.... GOSH has been in legal disputes in the United States, where the copyright term is based on date of publication, putting the 1911 novel in the public domain, although the Hospital asserts that the 1928 version of the play is still under copyright in the U.S.")
Rowling tied it all together. Like Barrie, she's an author of children's literature. (The production number more generally celebrated Britain's children's literature, e.g., "Mary Poppins.") Like Barrie, Rowling represents giving up one's money to the greater good. Barrie voluntarily donated a specific flow of money — "Peter Pan" royalties — to a specific cause — a children's hospital. Rowling is just a very rich person who — visibly and graciously — submits to taxation.
This year's Forbes magazine rich list showed that Rowling "has dropped out of the world's exclusive billionaires' club as a result of Britain's high tax regime."
So, fathom that: The government has gotten its arms around her fortune. Unlike the charitable giving of yore — exemplified by Barrie — the modern-day secular saint need only sit still for taxation, and the government will decide exactly where it goes. It's the way things are done now, and it's massively celebrated as part of the Olympics spectacle about what makes Great Britain so great. The spectacle notably took us through the phrases of history, and those wonderful children's authors have been giving children reading material and vast donations of wealth, in their own way and in their own time. And in our time, the government has an immense role.
"No man ought to graspe more then he can well fathome." Bp. J. Hall Horæ Vacivæ 71 (1646)(via OED).