Mr. White was a pre-War ghoul, a former radio host. He held a grudge against pre-War Wayne Newton, otherwise known as Mr. Las Vegas. Wayne was offered by Robert House... an opportunity to be immortal. He said that if Wayne agreed to have his personality used as an AI, then Wayne would essentially be immortal.
Mr. White was not the happiest person that he was not offered such a legacy, and as such, when the bombs fell, Mr. White made sure that he was transformed into a Ghoul so that he could undertake his revenge, and also have his legacy preserved in the books of the Wasteland.