Why is Faber so critical of himself and pessimistic about the world when he is first introduced in Fahrenheit 451?

Faber believes he is guilty by having been silent when the
fictional society in Fahrenheit 451 began to deteriorate, and books
became demonized, professors and authors and teachers were arrested or killed or driven
into exile.  He feels badly about himself for not trying harder to prevent
it.

Now, as the firemen burn house after house and war
drifts closer, Faber sees little hope.  He feels too old to do anything now but live
with his guilt, and until Montag reveals his own crisis of conscience, that there is no
one to help him fight back.

This is why he agrees to talk
Montag through his next meeting with Captain Beatty and with Montag's wife and friends
at their house, he sees a glimmer that he might be able to restart peoples' ability to
think and question independently again.