C. F. Keil and Franz Delitzsch on Proverbs 28:11

Pro 28:11 11 A rich man deems himself wise;      But a poor man that hath understanding searcheth him out, or, as we have translated, Pro 18:17, goes to the bottom of him, whereby is probably thought of the case that he seeks to use him as a means to an ignoble end. The rich man appears in his own eyes to be a wise man, i.e., in his self-delusion he thinks that he is so; but if he has anything to do with a poor man who has intelligence, then he is seen through by him. Wisdom is a gift not depending on any earthly possession.