Riches is Sin?

Helaman 4:11-12 [Book of Mormon]
“Now this great loss of the Nephites, and the great slaughter which was among them, would not have happened had it not been for their wickedness and their abomination which was among them; yea, and it was among those also who professed to belong to the church of God. And it was because of the pride of their hearts, because of their exceeding riches, yea, it was because of their oppression to the poor, withholding their food from the hungry, withholding their clothing from the naked, and smiting their humble brethren upon the cheek, making a mock of that which was sacred, denying the spirit of prophecy and of revelation, murdering, plundering, lying, stealing, committing adultery, rising up in great contentions, and deserting away into the land of Nephi, among the Lamanites.”
Where to begin….. a poor mimic of Old Testament themes of God visiting the children of Israel with defeat in battle when they break a covenant he made with them, and only them. I mean one wonders, were not these sins just as prevelant among the fictional Lamenites. In the Old Testament God gives victory to people such as the Babylonians, they were as guilty if not more guilty than the Israelites of the same sins. But God had not made a covenant with the Babylonians. Her in this book you have lamanites and Nephites, both of common ancestry, both come over under the same agreement with God, supposedly. So why does he favor the Lamenites in battle again?... It doesn’t make sense.
Furthermore, the list of sins. Most of them are infact sins, though I’m not sure about this immigration bit. But since when is being rich a sin? David and Solomon were rich. Abraham was rich. Countless other saintly people, believers in God have been rich. I happen to know a few rich Mormons. Monson does not seem to be suffering want. One has to ask if Mormon’s really believe in the Book of Mormon when they celebrate the rich, take for instance the late Larry H. Miller. May I mention the wealth of Brigham Young?
I’ll tell you another sin, declaring to be sin that which God has not declared to be sin.