Try starting at about "Part 3 The Big Lie; 3.1 What was the Big Lie?"
It explains it in detail there.
Basically players who go for exp rather than gold will get more gold over the long term. Gold is NOT Linear best way to see this is in the Guard Duty Payments
here
As you can see a lvl 20 gets over 4 times that of a level 10 and the difference increases even more as you go up the levels.