Does this mean that anybody who is really paranoid doesn’t need to be? Their emotions just tell them they do? So they don’t need that third party software?
Paranoia is emotion-based and completely irrational. Computer security decisions are largely made based upon emotions, and not reality. That is why most security software marketing targets peoples' fear of the unknown.
To answer your questions, really paranoid people are not behaving rationally. They do not need to be paranoid. They are being ruled by their emotions instead of reason.
Reason looks at reality and data. The real world data proves that systems are not being infected left and right. This is despite the never ending daily news reports of the next latest greatest most dangerous malware and data breach. The reason your system probably has never been infected is because probabilities are in your greatly in favor of you not getting a computer infection.
People want to feel safe. They do that by doing stuff that they think gives them control. That is not security. It is a whoopee blanket.