Some people control conversations so that the only agenda is theirs.
(i) I met a conspiracy theorist who engaged in monologues in which he only convinced himself. The same points were simply repeated endlessly. If the Moon Landing, to take one example, had been such an obvious fake, then it would not have fooled scientists, astronomers, investigative journalists, opponents of the US or critics of its government's policies. A conspiracy theorist can state arguments to which the uninformed cannot reply - until they google the issue. Then it emerges, to take another example, that, although the impact of an airplane on either of the Twin Towers could not have weakened its steel beams, the heat from burning fuel did.
(ii) A second way to control a conversation is to ask questions with the implication that the other party is insufficiently informed because he cannot give the answers required. I asked a master of this technique to tell me what he knew instead of asking me it and he replied that I didn't want to know.