Relative mobility has remained flat and absolute mobility has increased.

http://obs.rc.fas.harvard.edu/chetty/mobility_trends.pdf

Not actually the point I was making but an interesting paper nonetheless.

When I said "relative" I meant "relative to the population as a whole", not "relative to the members of one's class from prior generations."

Financially successful doesn't necessarily mean the same thing as being financially "successful relative to the rest of the population", for what it's worth.