I looked it up online. I think some of my family members have this, and to some extent, myself. I think having a healthy amount of paranoia is better compared to having 0 paranoia, like having no sense of safety. Paranoia prevents you from trusting people with mal intent, such as phishers and scammers. But too much is bad too.
I am not sure what cure there is for Paranoid Personality Disorder. But I think the environment has a big impact on mental development. Being surrounded by nice, trustworthy people could lessen the paranoia.