Delusion is generally bad; one gets into a state of denial which negatively affects one's life. An example is the teenage love-bird not accepting that the relationship is over.
However, getting into a state of informed delusion is equally bad if not worse. A great example is the doctor or personal trainer who knows that eating tons of cheeseburgers is bad for you, but does so anyway. There's this little part of the mind that somehow manages to convince the whole that having knowledge is the ultimate prudence.
However, some delusions are great. After all, where would we be if people didn't have the stubbornness to pursue their delusions of grandeur. That's what we need: to inform our delusions, and not let them inform us.
Send the PDF to someone under informed delusion