they are not selling their bitcoins to get bitcoingold rather they are buying bitcoins to get bitcoin gold equivalent to their current bitcoin balance and thats how it works just like happened on the past bitcoincash fork but i see they are having a hard time on this bitcoingold trend because some says this coin is not worth it and many says it was a scam, many speculators and news circulating now on the web and on the forum about btg so i guess lets just have to wait for the final announcement on what is the best thing to do about this.