Why do so many professing Christians read the book of Psalm and try to apply it to themselves as members...?

I have always felt the Psalms were meant to comfort, a book of prayers, as many of us go through certain things, these Psalms can offer comfort and solace & encouragement...I do not fully understand your "theory" or perception...what exactly are you attempting to get across, maybe it's just "me"?, I am sleepy so...nighty night :-)