And in 2010 Beyonce would be Top 3 seeing as how shes made $254 million from Jun '08 to Jun '10 alone.
It's naive of you to think Madonna is only worth that much... In your own words don't believe everything you read. It had also been said that Janet was worth $150 million and that's not true either. The people writing that stuff don't know much more about these ladies' net worths than we do.
This isn't a list of how much money these women ACTUALLY have in the bank, it's an accumulation of assets, catalogs, products, movies, and basically anything that has their names associated to it.
So it's more about their total career net worth, not how much they would be worth now. Take the Queen of the Netherlands for example her assets are said to worth over 3 Billion, but she has less than $300 Million to her actual name.
And it doesn't matter who has the most endorsements as of right now, when you take inflation into account of course Madonna, Mariah, and Celine would be above Beyonce, who arguably has the most endorsements right now out of the three. Not to mention Madonna and Mariah, I believe, own a lot of their song collections..and Celine is a tour-money-making machine.