No, he is saying that $1B in wealth (about 400 people) generates $77m (threshold to make list of highest earners) in income assuming a 7.7% rate of return (which seems unrealistically high to me).
Actually, I'm saying that if the 200+ Americans with >$2 billion in wealth consistently generated more than 4% return on capital, then at least 50% of the top 400 earners should stay relatively the same year after year (since those with >$2 billion usually stay billionaires). The fact that only 27% have appeared more than once suggests that those with more than $2 billion in net worth are reporting returns less than 4%.
Appreciating assets don't count as income. They very well may be minimizing income while still maintaining growth. When they sell those assets, they make the list.
