What about knowledge for the sake of knowledge? For instance I don't anticipate that my belief that The Crusades took place will ever directly affect my sensory experiences in any way. Does that then mean that this belief is completely worthless and on the same level as the belief in ghosts, psychics, phlogiston, etc.?

Wouldn't taking your chain of reasoning to its logical conclusion require one to "evict" all beliefs in everything that one has not, and does not anticipate to, personally see, hear, smell, taste, or touch? After all, how much personal sensory experience do you have that confirms the existence of atoms, for example?

DP