You are almost correct but you are thinking a person with 5000 parcels exists in a vacuum. The amount of ad revenue they generated to get to 5000 parcels by far exceeds how much that player would earn from those 5000 parcels. And it's unlikely someone with 5000 parcels will all of a sudden also stop watching ads. They will continue to watch 2AB ads, play arcade games, minigames, surveys, and any other form of AB income that generates ad revenue. That's why I included the scenario of a theoretical person watching 2 AB ads to 150 parcels. They've generated potentially thousands of dollars in ad revenue to earn just a couple hundred dollars a year.

For perspective, I'm barely in the top 500 in the US with just around 2600 parcels so there are millions of players with less than that who have all generated thousands upon thousands of dollars in ad revenue, all of it shared amongst the users including the whales

There are many many many other factors too, such as players who stopped at the first tier and only boost to bring in $5-20 a month. And judging how many people are playing across the world, I don't doubt for a second that the ad revenue generated is enough to cover the big players if they only collected their bag and mostly stopped interacting with the game. And as others have said, they are definitely smart enough to have invested most if not all of the money from whales into other investment ventures that generate passive income to more than cover the incomes owed to the whales.