https://www.apa.org/pubs/journals/releases/bul-bul0000392.pdf
From a summary of the paper:
The researchers found that overall, people were motivated to believe in conspiracy theories by a need to understand and feel safe in their environment and a need to feel like the community they identify with is superior to others.
The researchers also found that people with certain personality traits, such as a sense of antagonism toward others and high levels of paranoia, were more prone to believe conspiracy theories.
Those who strongly believed in conspiracy theories were also more likely to be insecure, paranoid, emotionally volatile, impulsive, suspicious, withdrawn, manipulative, egocentric and eccentric.