Or do they merely pay lip service to the idea? I have no doubt that some of them sincerely believe. But when I was a kid, growing up in the '80s, I didn't know of a single witness, myself included, who didn't believe the end was close. But I just don't see that attitude prevalent today. At least it isn't reflected in their behavior, or the way they live their lives.
A prime example of this is my oldest brother. He is one of the most hardcore dubs that I know. He is presiding overseer of his cong, and a substitute CO. He and his wife have been regular pioneers for over 20 years. And yet, he also has been planning for the future by putting money into an IRA account. It seems somewhat contradictory to me to go to people's homes, and warn of impending doom, while at the same time, saving for a retirement, some 20+ years in the future. I suspect that there are many others like my brother, who are beginning to doubt if armageddon will come in their lifetime, if at all. They are simply going through the motions, either to appease family and the elders, or because(which is more likely in my brother's case) they have simply invested too much of themselves to leave, and find something else.