It's always about desire.
When a human wants something, there's little that they won't do to get it. This old guy is the person controlling the people controlling Japan, yet they know they can't even look at a Primal Devil in the eyes, much less ask why he'd use their boss as a chair. Whereas most people asked Denji why he'd let let others sit on him for so little.
Difference is, this guy is really powerful in society, whereas Denji has little to no knowledge of the world and is trying to get money in ways that he understands. But make no mistake, they're the same. They're both doing away with their pride for their objective. It's just that this old guy has a really selfish wish. Just like the realization that Denji had in the very first chapter "everyone has dreams".
