That's a lovely chart, but it doesn't seem to be using solar time? I wake just as the sun stretches over the horizon and peeks though my window. In the summer, it's very early; in the winter, it's quite late.

If we're to set the start for the official day, it should probably happen an hour or so after the sun has risen. Sadly, on the western side of time zones, like Grand Rapids MI, it's often pitch black when the workday starts.

I can choose to believe that graph, or I can choose to believe it's getting something wrong and the majority of people want to get up relatively early. For whatever reason that may be. If the early risers were indeed such a minority, how exactly are they forcing the vast majority to conform?

Idk, how is the rich minority forcing the rest of humanity to slave away dusk till dawn to buy them superyachts and private islands?

By being the ones in position of authority of course. It doesn't take more than one or two examples for the rest of the world to copy something verbatim out of practical conformist reasons.