Plagiarism has serious consequences.
Plagiarizing another source can lead to failing an assignment, failing a class, getting suspended from school, or even getting permanently expelled. There are very rarely second chances when one plagiarizes.
Plagiarism is unethical because the plagiarizer is essentially stealing work from the original author and gaining all of the benefits that the original author worked hard to obtain.
Once you are caught plagiarizing, it will be hard to earn back the trust and respect or the reputation that you once had.