1)
What does the verse teach about those who trust in their wealth?
1.
Rashi: Their wealth will not help them [like verse 8 says].
2.
Radak: They trust in their wealth and pride themselves about it. I should not do so; one may boast only about being wise to know Hashem (Yirmeyah 9:22-23).
3.
Malbim: They do not trust in it to be a means towards perfection, e.g. to do Tzedakah and Chesed. Rather, they boast about their great wealth; this is their purpose for amassing great wealth.