The substance of a rich man is the city of his strength: the fear of the poor is their poverty.

The wealth of the rich is his strong city, The ruin of the poor is their poverty.

The property of the man of wealth is his strong town: the poor man's need is his destruction.

The substance of the rich is the city of his strength. The fear of the poor is their destitution.

Destruction - That which crushes, throws into ruins. Wealth secures its possessors against many dangers; poverty exposes men to worse evils than itself, meanness, servility, and cowardice. Below the surface there lies, it may be, a grave irony against the rich; see Proverbs 18:11.

The rich man's wealth is his strong city - Behold a mystery in providence; there is not a rich man on earth but becomes such by means of the poor! Property comes from the labor of the poor, and the king himself is served of the field. How unjust, diabolically so, is it to despise or oppress those by whose labor all property is acquired!
The destruction of the poor is their poverty - A man in abject poverty never arises out of this pit. They have no nucleus about which property may aggregate. The poet spoke well: -
Haud facile emergunt, quorum virtutibus obstat
Res angusta domi.
"They rarely emerge from poverty, whose exertions are cramped by want at home."

The rich man's wealth [is] his (h) strong city: the destruction of the poor [is] their poverty.
(h) And so makes him bold to do evil, while poverty bridles the poor from many evil things.

The rich man's wealth is his strong city,.... What a fortified city is to persons in time of war, that is a rich man's wealth to him; by it he can defend himself from the injuries of others, and support himself and family in times of public calamity; for money is a defence, and answers all things, Ecclesiastes 7:12. Or his wealth is so in his own apprehension and conceit; he puts his trust and confidence in it, and thinks himself safe and secure by it; when he is trusting to uncertain riches, which will fail him; these may fly away from him in life, and leave him exposed to distress and danger; and, however, will not secure him at death from the wrath of God and everlasting destruction. Or he is lifted up with his riches, is in high spirits, and despises others; thinking himself safe, as in a strong castle, and fears nothing, distresses, diseases, or death;
the destruction of the poor is their poverty: or their poverty is their consternation, as the word (h) signifies, it frightens them; they, knowing their circumstances, are afraid of everybody and of every thing; not being able to defend themselves against their enemies, or support themselves in times of public calamity, as war, famine, or pestilence.
(h) "consternatio", Mercerus, Gejerus, Michaelis.

This refers to the common mistakes both of rich and poor, as to their outward condition. Rich people's wealth exposes them to many dangers; while a poor man may live comfortably, if he is content, keeps a good conscience, and lives by faith.

Both by trusting in "uncertain riches" (1-Timothy 6:17), or by the evils of poverty (Proverbs 30:9), men, not fearing God, fall into dangers.

A pair of proverbs regarding possession and gain.
Regarding possession:
The rich man's wealth is his strong city;
The destruction of the poor is their poverty.
The first line = Proverbs 18:11. One may render the idea according to that which is internal, and according to that which is external; and the proverb remains in both cases true. As עז may mean, of itself alone, power, as means of protection, or a bulwark (Psalm 8:3), or the consciousness of power, high feeling, pride (Judges 5:21); so קרית עזּו may be rendered as an object of self-confidence, and מחתּה, on the contrary, as an object of terror (Jeremiah 48:39): the rich man, to whom his estate (vid., on הון, p. 63) affords a sure reserve and an abundant source of help, can appear confident and go forth energetically; on the contrary, the poor man is timid and bashful, and is easily dejected and discouraged. Thus e.g., Oetinger and Hitzig. But the objective interpretation is allowable, and lies also much nearer: the rich man stands thus independent, changes and adversities cannot so easily overthrow him, he is also raised above many hazards and temptations; on the contrary, the poor man is overthrown by little misfortunes, and his despairing endeavours to save himself, when they fail, ruin him completely, and perhaps make him at the same time a moral outlaw. It is quite an experienced fact which this proverb expresses, but one from which the double doctrine is easily derived: (1) That it is not only advised, but also commanded, that man make the firm establishing of his external life-position the aim of his endeavour; (2) That one ought to treat with forbearance the humble man; and if he always sinks deeper and deeper, one ought not to judge him with unmerciful harshness and in proud self-exaltation.

Wealth - It often redeems him from dangers and calamities. Poverty - Is the cause of their ruin.