I doubt he sold the book rights outright without an ongoing royalty. He may not have benefited personally from the sales in his lifetime as much as his legacy

I doubt he sold the book rights outright without an ongoing royalty. He may not have benefited personally from the sales in his lifetime as much as his legacy would seem to owe him, but I imagine his estate (and its agents) have done perfectly well by it. According to this article, they have: http://theamericanscholar.org/living-on-500000-a-year/ http://theamericanscholar.org/living-on-500000-a-year/. Film rights may not have included a royalty, and even if they did have historically been more subject to "creative accounting".