How can someone who is considered wise or a 'knower' still fall into sin and wrong actions?

The source explains that even great knowers can have their intellect corrupted and experience a downfall. This happens because Maya can cover self-luminous knowledge just as Rahu eclipses the moon or moss covers water. As Chapter 50 describes, these individuals know the remedies but fail to hold firm, instead behaving according to their whims. They may know perfectly well that committing a sin is an act of ignorance, but Desire (Kama) is the ultimate cause of activity, and it can override their knowledge. They become deluded about what should and should not be done, drawn to sin like a moth to a flame, and can be ruined by bad company.