KJV: A man that hath friends must show himself friendly: and there is a friend that sticketh closer than a brother.
NIV/ESV: A man of many companions may come to ruin, but there is a friend who sticks closer than a brother.
There is another possible way to view the Hebrew here in that the key Hithpael-stem verb may mean "broken" in an idiomatic sense (I haven't verified an idiom). The concept of "broken in spirit" produces a selfless nature in people that is conducive to making friends, common arrogance of the human mind being out of sight. Hasidic Rabbi Menachem Mendel said "there is nothing so whole as a broken heart," which is a state of mind that others are drawn to and is very conducive to creating loving friendships. Indeed in Matthew 22:39 Christ said the second great principle of the law is to love our neighbor as ourselves, and a broken spirit is just what makes this possible. Further, Philippians 2:3 tells us to consider others as better than ourselves, and this would be the ultimate state conducive to loving friendships.
Thus the modern-version concept that the hithpael verb speaks of a state of ruin due to making unwise friendships would be an overly-literal approach to translating Proverbs 18:24, one that misses the actual sense of the teaching. Even so, the reflexive nature of the hithpael verb would apply, and the rendering of the KJV, "A man that hath friends must show himself friendly" (by his humble spirit) would be appropriate. That would mean that the second clause of the verse speaks of a friendship even greater than this, that of mankind with the Lord God. Indeed Psalm 51:17 says, "The sacrifices of God are a broken heart: a broken and a contrite heart, O God, thou wilt not despise." Thus the teaching of the Proverb would include the ultimate sense of friendship, instructing us to seek to follow on earth the type of friendship anticipated in heaven.