They stuck around after the WT's failures because they didn't have the cajones to admit they had been made fools of.
Did you listen to the interviews with Harold Camping's followers after the rapture never arrived? Same logic, different cult. Followers so wanting not to admit they had been stupid in giving their life's saving to a loser, that they still maintained that Camping had some kind of Devinely inspired purpose and still were not prepared to abandon him.