Naively, people have been working for 75 years over the span of the graph to create valuable IP, scalable manufacturing, unique organisational capabilities, partnerships etc.
If capital is being created faster than it degrades or is destroyed, wouldn't we expect its share of income to increase over time?
It's not obvious to me why labour's share should necessarily remain constant as the economy accumulates hard-to-replicate productive assets.
Because society breaks down when there is an elite class of people who are so wealthy the law no longer applies to them, while a significant portion of people are on the brink of being homeless, and many more are one health emergency away from it.