It is not plagiarism because no one owns those type of phrases or words which appear in speeches given by athletes, actors, students, anybody who was ever proud of what they accomplished. I think many live in a nitpicking, critical world of pure lunacy especially the disingenuous MSM.
You are confusing the issue.
This is not about who owns the copyright to the words. It is not about an actionable cause based on plagiarism.
It is about an intentional use of Michelle’s speech AND WHY it was done.
Why can NO ONE point me to anyone else who has used this EXACT phrase in this EXACT way except Melania and Michelle
““”that you work hard for what you want in life, that your word is your bond and you do what you say “”
The latter shows how to use this whole hoopla to clear advantage.