Proverbs 9:18 New English Translation

¹⁸But they do not realize^[a] that the dead^[b] are there,
that her guests are in the depths of the grave.^[c]

Proverbs 9:18 tn Heb “he does not know.”
Proverbs 9:18 sn The “dead” are the Rephaim, the “shades” or dead persons who lead a shadowy existence in Sheol (e.g., Prov 2:18-19; Job 3:13-19; Ps 88:5; Isa 14:9-11). This approximates an “as-if” motif of wisdom literature: The ones ensnared in folly are as good as in Hell. See also Ptah-hotep’s sayings (ANET 412-414).
Proverbs 9:18 tc The LXX adds to the end of v. 18: “But turn away, linger not in the place, neither set your eye on her: for thus will you go through alien water, but abstain from alien water, drink not from an alien fountain, that you may live long, that years of life may be added to you.”sn The text has “in the depths of Sheol” (בְּעִמְקֵי שְׁאוֹל, b^eʿimqe sh^eʾol). The parallelism stresses that those who turn to this way of life are ignorant and doomed. It may signal a literal death lying ahead in the not too distant future, but it is more likely an analogy. The point is that the life of folly, a life of undisciplined, immoral, riotous living, runs counter to God’s appeal for wisdom and leads to ruin. That is the broad way that leads to destruction.

New English Translation (NET)