A chapter by chapter verse by verse study of the book of Proverbs.

When it comes to the Bible, few books are more practical than the Book of Proverbs. Proverbs is loaded with hundreds of short, powerful persuasive instructions to be acted on for their practical value in life. They give us guidance for day to day living. However, it seems that most people are merely scratching the surface of Proverbs. Most people seek advice from Proverbs. But to really benefit from Proverbs, we need to also seek wisdom, and there is a difference.
Through the centuries, many Christians have turned to the book of Proverbs for wisdom. That is, essentially, what the book is about. It was written at the highpoint of Israel’s history with the gift of wisdom bestowed upon her king, the book encourages the pursuit and gaining of wisdom. At all costs, “get wisdom”  Our goal is to get better acquainted with Proverbs and the wisdom it offers.
In our last study we concluded with verse 10,
The name of the LORD is a strong tower: the righteous runneth (run) into (to) it, and is (are) safe.
Proverbs 18:10   
We talked about the power of the LORD’s name and many of the the things we are saved from. The LORD is our refuge.
As we continue with verse 11 an alternative refuge is now presented. "Wealth!" And though wealth does provide some security, but we need to be careful not to fall into the trap of falsely imagineing that it is a stronger safeguard against adversity, affliction, and misfortune, than it really is,
The rich man's wealth is his strong city, and as (like) an (a) high wall in his own conceit (esteem, imagination).
Proverbs 18:11   
In contrast to the righteous who find their strong tower in the LORD and His character, the rich man (here used in the sense of the man who trusts in his riches, who is only rich and nothing else) finds refuge in his wealth. Such a man who trusts in his own riches has no refuge when they fail.
The protection wealth offers is like a high wall only in His own estimation.  The rich man sees his wealth as safe and sure as a high wall around a strong city. Yet this is only in his own estimation; both the Lord and the wise know that wealth is not a truly strong city and not a high wall. Don't trust riches.  A rich man's wealth is different from the strength that the righteous have in the Lord.  He has got to depend upon his money.  The money can disappear and that is why Jesus was constantly warning the rich all throughout the New Testament and through proverbs, and especially in James too, there are many warnings for rich people to trust God.