Ayers inherited wealth.
“Then, unprompted he said—I wrote Dreams From My Father. I said, oh, so you admit it. He said—Michelle asked me to. I looked at him. He seemed eager. He’s about my height, short. He went on to say—and if you can prove it, we can split the royalties.”
http://backyardconservative.blogspot.com/2009/10/bill-ayers-no-dream.html