The Bill Gates and Larry/Sergeys of the world are rich because they are business owners, not because they are programmers. The sports equivalent would be if Michael Jordan started his own basketball league, grew it to many teams/cities, got TV and merchandising contracts, etc.
Sports stars are some of the highest payed employees in the world because they, like musicians and movie stars, can use the infrastructure that mechanical_fish mentioned. But they are nowhere near as wealthy as the team owners, just like great programmers that aren't also business owners aren't nearly as wealthy as the companies that employ them.
Michael Jordan is part-owner of the Charlotte Bobcats, actually, and I think there are a number of Google and Microsoft employees who are richer than Michael Jordan (who apparently has about US$400M and recently had to pay US$168M in a divorce settlement). It's true that it's because they're part-owners of Google and Microsoft, but that ownership was granted because of work they did, not (for the most part) because of dollars they contributed.
So I think the premise of the article is wrong; some programmers do earn as much as sports stars and star musicians. I don't have a good sense for how the numbers shake out in the aggregate.
Sports stars are some of the highest payed employees in the world because they, like musicians and movie stars, can use the infrastructure that mechanical_fish mentioned. But they are nowhere near as wealthy as the team owners, just like great programmers that aren't also business owners aren't nearly as wealthy as the companies that employ them.