Those who follow the "tax protestor" -- actually, tax denial -- movement know they are deeply conspiratorial. Everything is part of an awful conspiracy, including the exact typeface used on letters they receive. In the immortal words of Aldous Huxley, paranoids live "in a world of terrifying significance."
While it is possible that some of the people who believe in conspiracy theory are actually paranoid (in the clinical sense), for most it fills some other psychological need -- in paricular, the need to explain away the inevitable failures and disappointments of life as a nefarious plot against them, and the need to feel important for being "in on the secret".
For this, any conspiracy theory will do. It is no surprise that tax protestors often believe in many other conspiracies -- such as in The Protocols of the Learned Elders of Zion (or its modern equivalents, replacing "Jews control the world" with "Zionists control the USA"), 9/11 conspiracy theories (decisively exploded here, for example), and so on.
Labels: tax protestor