The wisdom of the Torah is freely available to everyone, yet there are certain individuals who simply cannot be corrected. A wise person must be careful not to waste energy on those who actively oppose the truth. Attempting to guide such people is not only doomed to fail, but it also brings direct harm to the one offering the guidance.
There is a specific type of arrogant individual who mocks others out of excessive self-confidence and rejects any authority based on faith [ביאור שטיינזלץ, מלבי״ם]. The primary approach among commentators is that trying to teach morals to such a person only results in shame and disgrace for the teacher. Instead of listening, this arrogant person will respond with mockery and insults. However, another perspective suggests that the shame comes from the manner of the rebuke itself. If a person delivers criticism through joking and mockery, he invites insults and brings disgrace upon himself [אבן עזרא].
An even lower level of character is the intentionally wicked person. This individual is entirely corrupt and rejects even basic logic and common sense [מלבי״ם, אבן עזרא]. Just as correcting a mocker brings shame, attempting to correct a wicked person results in a lasting blemish [עמנואל הרומי, מלבי״ם]. The primary approach among commentators is that this blemish attaches to the person giving the rebuke. When corrected, a wicked person will launch a personal attack, actively trying to expose the teacher's own faults and claiming that the teacher is just as guilty [מצודת דוד, עמנואל הרומי]. This serves as a strong warning that one must be extremely careful not to criticize another for a fault that they themselves possess, or they will face stinging insults and be told to fix their own flaws first [אלשיך]. Conversely, another view suggests the blemish belongs to the wicked person, who either firmly believes his actions are flawless or is aware of his faults but deeply hates having them exposed [אבן עזרא].
Beyond the danger of personal insults, the very act of arguing with arrogant and wicked individuals is considered a flaw for a wise person. Much like the prophets of Israel who suffered abuse when their messages fell on deaf ears, anyone who shares wisdom with those who refuse to listen ultimately degrades that wisdom [אמרי דעת]. Therefore, this serves as a strict warning to completely avoid people who lead others astray, rather than attempting to draw them close or correct their behavior [רש״י].