Having read the "primary research" of Tom Purvis, and inasmuch as I do "appreciate" his amazing work, I would have to disagree.
Oxford defines "cynic" as "a person who believes that people are motivated purely by self interest rather than acting for honorable or unselfish reasons."
Bugliosi, Mailer, Posner - plagiarist who presented "secondary " research as "primary" - and others certainly come to mind.
"Cynic"? Yes, I am guilty as charged. Happily so. 
Bugliosi, Mailer and Posner all interviewed numerous witnesses, some who were never interviewed before, and found primary sources of information on the assassination, directly and indirectly.
For example, Mailer interviewed the Belarus KGB agents who monitored Oswald. And also many of the associates that Oswald knew when he was in Minsk. And he (Mailer) read the KGB files on Oswald. This was all original material/information.
Posner interviewed, among others, Yuri Nosenko. Bugliosi interviewed McClelland and got him to admit that the head wound was further forward then in the sketch he (incorrectly) claimed that he did for Thompson.
To simply dismiss these works as "secondary" research is short sighted.
As to cynicism: I think if you told a cynic that dozens (hundreds?) of people remained silent for decades after committing or being in involved in a terrible act even though they could have made money and fame by exposing it later he'd laugh you off as being a naive fool.
