This one was an extreme case, even for a politician. Most likely really mentally ill, suffering from paranoia. His stories felt credible and sincere (I wouldn't be surprised if this is true in general for intelligent paranoid people), and he started very popular, but gradually more and more people noticed that his words don't match well with reality, and not even with his previous words. At the end mostly the old people remained loyal to him, so we say cynically that his political base died of old age. I guess that unlike many politicians, this one probably truly believed what he said.