To start with, the first photo was a mock-up, not an actual interior. And a lot of the headroom was at the expense of center overhead bins. And the overhead bins on the sides were much smaller.
The airlines made the money to afford this in two ways. First, with so many passengers on board, the per passenger cost was about halved, as long as jet fuel prices stayed low. The other thing was that 747s could carry a LOT of cargo, which was also big money.
The two things that stopped it dead in its tracks were the OPEC oil embargo, and Jimmy Carter’s double digit inflation. Both of which, truthfully, could be blamed on Carter, because OPEC, and everybody else, saw him as weak and spineless. Which he was.
Carter really derailed America from its course to the future. By the end of his time in office, the country was in spiritual depression. Fortunately, Ronald Reagan did much to bring us back, for which he is beloved.
Carter is just remembered as a pathetic man, a failure as a president and a person.
Carter stunk, but inflation took off when Nixon closed the gold window. However, Nixon had no choice. France was threatening to exchange all their dollars for gold which was set at an artificial rate that the United States could not honor in any large quantity.
The whole inflation time bomb was set up by the Fed printing money in the several years after WWII and keeping interest rates artificially low, the Bretton Woods agreement, and all the big government spending of the 1960's. Nixon was in the wrong place at the wrong time, as was Carter. They were both vulnerable to OPEC. However they both could have deregulated the oil industry as Reagan did, and avoided stupidity like price controls.