Actually, the above rephrasing is wrong and completely changes the meaning. The original author wasn't saying poor people have less clutter he was saying they have more, but for a reason. Maybe this wording is clearer:
The reason poor people have clutter isn't because they're too dumb to see the virtue of living simply, they have it to reduce risk.
The reason poor people have clutter isn't because they're too dumb to see the virtue of living simply, they have it to reduce risk.