To satisfy family members over Christmas.

"I'm sorry I can't join the family meal, I have tested positive"

>Exactly, these devices are meant for personal use. Why would you want to fiddle with the results?

My experience has been that you can at least get a day off depending on your organisation's policy or until you receive a negative result on a PCR confirmation test. Think perhaps about that business trip that you really don't want to make. I remember reading reports on schoolchildren coming up with chemical solutions (IIRC cola) to fake positive covid testing results in order to skip school. A slightly "techier" covid testing product like the one from the article might placate a more suspicious employer.

I was wondering that... Potentially where the implications of quarantine are not as bad, as say, going to work? Or maybe to inconvenience someone?

Maybe insurance fraud? If you were somehow covered or wanted a refund on some travel. But again, I can't imagine a policy which explicitly covers COVID being beneficial for the underwriter.

In some areas, testing positive means paid leave.

Here, such devices are used for testing kids at basic school. I heard a story from one of our managers that some kid in his kids' class wanted to fake his test to read positive (to evade school duties) so he used a pen marker however this attempt was discovered :-)