Conspiracies are sometimes concerned with an event, like the Moon landing, but in modern times the idea that a group of people have an agenda, a systemic conspiracy, has taken hold. Maybe it is left over from the 1960s and all those James Bond movies. People who are anti-science about food, for example, will try to claim they love science but that Monsanto and others groups are trying to take over the world and control the food supply.
Cui bono? is Latin and means 'for whose benefit?' Systemic conspiracy theorists find an event, and then find someone who benefited from that event, then they claim the group that benefited caused the event.
Climate skeptics and anti-GMO activists are groups who frequently invoke a systemic conspiracy but as the graphic shows, this is big in economics too.