I certainly know of people for whom this is true, specifically for religious beliefs which they have grown up with and devoted a large portion of their life to.
As for myself, I try to keep a distinction between believing things to be true, and acting as if they were. In general I tend to be optimistic about people, plans, etc: not because I actually, seriously believe things will always turn out well, but simply because I find it a more pleasant way to go through life. The positive results of the few long shots which pay off outweigh the negative results of the majority which don't, in the final subjective impression.
no subject
As for myself, I try to keep a distinction between believing things to be true, and acting as if they were. In general I tend to be optimistic about people, plans, etc: not because I actually, seriously believe things will always turn out well, but simply because I find it a more pleasant way to go through life. The positive results of the few long shots which pay off outweigh the negative results of the majority which don't, in the final subjective impression.