Who cares that much about the salary when you are that point in the Software Engineeering career track in SV anyway? What, really, is the difference between making $300K/yr and even fully doubling that to $600K? A nicer apartment, a nicer car, an earlier retirement? These are pretty marginal things if the cost is spending most of your time doing something you don't like.
The most common reason somebody becomes an EM that I've observed is because somebody else tells them to do it. It's a promotion, so you should want it. I'm one of very few people in the SwE world I've encountered who very actively and clearly wants to do it, and for the reasons you listed - to spend more time on humans and less on code.
Most of my managers have at best tolerated the position; several have confessed being miserable and just wanting to code again ("okay, let's switch" hasn't worked, though). That includes my current and previous manager; the one before those 2 said he didn't want to manage and despite being CTO was trying to maneuver into more of an architect position, the one before that quit within a month of being promoted. I've known several people who were EMs and switched back, and had a friend confess that she was on the verge of quitting before she got offered the chance to be an IC again.
Not a one who got promoted and then loved it.
Given that it's true most ICs want to code and not manage (even if many can learn to be good managers), and these days big company ICs are very well compensated... it really feels like the driving force is external - somebody else tells them to do it, it looks like the natural progression, and that's "just what you do" more than anything else.