> Personally, I have never seen a case where tattoos improved someone's health, or appearance for that matter.

This is subjective. "Health" here might be taken to include mental health, in which case there could be many positive benefits.

That said, there are some objectively bad health outcomes that can come from getting tattoos [1, 2]. Not that they necessarily will.

[1] infections, autoimmune response, etc: https://onlinelibrary.wiley.com/doi/full/10.1111/jocd.14498

[2] lymphoma: https://www.medicalnewstoday.com/articles/tattoos-may-increa...