I understand the argument that the Quran is the word of God as told to Muhammad by the angel Gabriel, and, hence, enjoys divine protection and its message cannot be corrupted by mere humans. Hence, full belief in the Quran is mandatory.
But other stuff, such as hadiths, similar scriptures, folk stories, and other accounts made by so-called "scholars" are not similarly protected by the divine. They can be fabricated, untrustworthy, misleading, mistaken, and so and so forth, suffering from all the imperfections that define humanity.
So .... why do muslims believe them, especially when they are so fundamental in defining how a "proper muslim" should be, and thus paramount in the way in which a muslim lives their life?