Buddy...I have never said this to anyone on Medium before, and I'm wrestling with myself for saying it to you publicly now, instead of in a private email, but...
You underpaid your ghostwriter to a disgraceful degree.
You hired a ghostwriter to research AND write a book for you--and you paid him the princely sum of FIFTEEN DOLLARS?! That is one hour's worth of minimum-wage pay in California and two hours of minimum-wage pay in Texas. I hope your tip was substantial.
It took your ghostwriter two days, presumably 16 hours, to accomplish this feat for you. That is amazingly fast, but I'm guessing your book was short.
For your future information, professional ghostwriters can earn $700.00 for a 100-page project. Please keep that in mind the next time you want to hire a ghostwriter and expect that person to work for starveling wages.