Why do some people always treat the manas as if it were a fool?

The mind consciousness of the vast majority of people, lacking wisdom and lacking the wondrous wisdom of observing (pratyavekṣaṇā-jñāna), cannot observe the manas and therefore does not understand it, which is why they treat the manas as a fool. Only after consciousness is transformed into wisdom, when the mind consciousness possesses the wondrous wisdom of observing, can it directly perceive the operation of the manas, thereby uncovering the profound and subtle nature, functions, and mental factors (caittas) of the manas. However, transforming consciousness into wisdom requires attaining the meditative concentration of the first dhyāna, eradicating afflictions, becoming a bodhisattva of the first bhūmi or above, and possessing the seed-wisdom (bīja-jñāna) of Yogācāra; only when the mind consciousness is free of obstructions can it clearly observe the operation of the manas. At the same time, the manas has also undergone the transformation of consciousness into wisdom, possessing great wisdom, and its mental factors differ from those of pre-bhūmi bodhisattvas (pūrvabhūmika bodhisattva).