Theft is theft whether it involves words and ideas or physical property. Writers may think that representation of others' ideas in their own words is not plagiarism. Yet ideas are individually creative things and should be recognized as such. Crews and VanSant wrote, Writers sometimes plagiarize ideas from outside sources without realizing that they are doing so. Put simply, you plagiarize if you present other writers' words and ideas as your own.
Plagiarism is motivated out of self-interest.
Nearly every person has plagiarized, intentionally or unintentionally, at some time. Students can be taught not to plagiarize out of self-interest to achieve success. The process of finding words to copy, piecing the words together, and trying to achieve voice continuity is more difficult than reading, understanding and developing a thesis that represents an original idea. It is then in the self-interest of the student to take the easier, more rewarding route. It is like getting paid more for less work.