Most people do not believe in conspiracies. The truth is that the world is full of conspiracy. If there were no such thing as conspiracies, governments would not need Intelligence Agencies, which sit behind closed doors and secretly plot how to infiltrate another government to illegally gather intelligence. People who reject the reality of conspiracies either haven't thought the issue through, or don't want to believe that there are people who plot the enslavement or destruction of others. In fact conspiracies are part of every day life.
People conspire with work associates to advance their position over colleagues.
Politicians constantly conspire to win public favour, and personal gain. Government-sponsored human radiation experiments in the USA has been exposed. The CIA MK Ultra mind control program exposed in the late 1970's is another example of a cabal of people conspiring to implement an agenda the public would not approve. Plots and actions are constantly being exposed. Conspiracies are a fact of life.