There are people so absorbed in conspiracy theories that the world around them constantly seems a war zone. There are others so deeply buried in their own egos that they refuse to recognize and correct their odd actions and behaviors. There are even some so set in their ways that the mere thought of open-mindedness confounds them. Working for a bank, I see a lot of these people.
These people seem hopeless; they probably are. No matter what you say or do, there is no chance of saving them. Interactions with their kind go the smoothest when one plays the beta male and happily agrees with their statements, offering no counter points or resistance. It takes less energy, maintains the friendship, and avoids tension.
While playing the beta male has it benefits, it also diminishes the respect you have from those around you. They come to see you as flexible and weak. To avoid this downfall, try to challenge the hopeless instead. Lightly tease them, make them think about their choices and actions. Challenge their ideas in the same ways they challenge yours.
Why waste my time?
Force them to think. Force them to judge themselves. Force them to look for the logic in their own beliefs. When they find none, drive that point home.
If everyone only agreed with these people, it would add even more fuel to their oddities. The hopeless would only delve deeper into helplessness. Plus, running circles around them and proving your intellectual dominance is mighty fun.