My father is an elder, and I think a big reason he's so convinced it's 'the truth' is because he's hyper-humble. He has very little self confidence and therefore anything that he's able to achieve (giving talks, actually encouraging people in sheparding calls, whatever) is only due to god's spirit and has nothing to do with himself. The truth is, he's very smart and very kind and quite articulate and is an obvious choice if you're picking someone for the job that being an elder ostensibly is (being a kind, empathetic shepard to the flock) so it's no wonder that he's able to do such a good job.
Also, I suspect at his age, even if he had doubts he'd see the risk of losing out on the potential of a reserection would be too great for the few years of freedom he'd have if he left.
Ugh, I don't often get emotional, but thinking about the way my poor father's been abused could get me there if I keep going...It really is exactly like an abusive marriage. I definitely think there's some overlap in this topic and one on "why don't more abused wives leave?"