It does have its use case, especially since Things are so bloody expensive nowadays.

When a replacement car key costs $2000, some people may chose to pay $50 for a keyring that makes it easy to find them when the lose them down the back of the sofa, regardless of the privacy implications.

That said, I have never had to search for the two items I have an AirTag attached to; although an AirTag in my wallet would be handy.