Oh, I'm familiar with that; I thought that the parent meant that there are people who make money directly from the copyright on the patterns rather than the artifacts they sell. Are there?
As far as I know they sell the patterns, not the finished knitted artifact. Aspiring knitters buy them to enjoy knitting. The physical representation of the pattern isn't worth anything (just a piece of paper), what you're buying is a license to use their intellectual property, so I'd say they're making money from copyright.