What do we learn from "Hon Ashir Kiryas Uzo [uch'Chomah Nisgavah]"?
R. Yonah: A Tzadik trusts in Hashem, and an Ashir trusts in his wealth. The former brings salvation from affliction; the latter is a reason to fall from serenity. Therefore, the coming verse says "Lifnei Shever Yigbah Lev Ish", and it says "Bote'ach b'Ashro Hu Yipol" (11:28).
Malbim: An Ashir considers his wealth to be the city of his strength and a tall wall.
What is "Maskiso"?
Rashi: His house. Because it is tiled with stones that cover the ground, it is called Even Maskis.
R. Yonah #1: It is where he stores his silver and gold.
R. Yonah #2: This is like Machashavto, like "Maskiyos Levav" (Tehilim 73:7). Malbim - i.e. he only thinks that his wealth is a stronghold. He cannot run on this 'wall' or take refuge in it. It is only imaginary. Worldly acquisitions are imaginary; their foundation is in imagination.