There are many reasons for plagiarism. Many of the students do plagiarism just because they are not confident or they want good grades.

“Thirty-eight percent of the undergraduate students surveyed said that in the last year they had engaged in one or more instances of “cut-and-paste” plagiarism involving the internet, paraphrasing, or copying anywhere from a few sentences to a full paragraph from the Web without citing the source…Forty percent of students acknowledged plagiarizing written sources in the last year.”

In his 2004 book The Cheating Culture: Why More Americans Are Doing Wrong to Get Ahead, David Callahan attributes academic dishonesty to cultural messages that favor ruthlessness and competition as the only means to success.

Few common reasons for plagiarism:

  1. Pressure to earn or maintain better marks in some tough college courses.
  2. Competition to get a job.
  3. Due to hectic schedule or poor management of time.
  4. Less confidence to make an assignment by ownself.

References:

Callahan, D. (2004). The Cheating Culture: Why More Americans Are Doing Wrong to Get Ahead. Orlando, FL: Harvest Books.

https://teachingcommons.unt.edu/teaching-essentials/academic-integrity/why-do-students-cheat