Proverbs 18:1 New English Translation

18 One who has isolated himself^[a] seeks his own desires;^[b]
he rejects^[c] all sound judgment.

Proverbs 18:1 tn The Niphal participle functions substantively and has a reflexive nuance: “one who has separated himself” (cf. KJV, ASV, NASB). He is not merely anti-social; he is a problem for society since he will defy sound judgment. The Mishnah uses the verse to teach the necessity of being part of a community because people have social responsibilities and need each other (m. Avot 2:4).
Proverbs 18:1 tc The MT has “seeks [his own] desire[s].” The translation in the LXX represents a Hebrew Vorlage of לְתֹאֲנָה (l^etoʾanah) instead of לְתַאֲוָה (l^etaʾavah); this could be translated “seeks his own occasion,” that is, “his own pretext” (C. H. Toy, Proverbs [ICC], 354; cf. NAB). The MT makes sense as it stands and the emendation is not really necessary.
Proverbs 18:1 tn Heb “breaks out”; NRSV “showing contempt for”; NLT “snarling at.” This individual breaks out in contention against sound judgment. He is in opposition to society (e.g., Prov 17:14; 20:3).

New English Translation (NET)