As someone who is totally creeped out by needles I cannot see myself doing this. I don't have tattoos and I hate getting shots, having blood drawn, etc. But that doesn't mean someone else shouldn't do it. I don't like body art, or eating snails, or swimming in cold water. But that's just me and informs the things that I do. The woman with the key card implant is not me. She clearly enjoys making alterations to her body, and it's great that she can do those things.
It's stupid to call someone stupid for having different preferences. She's not stupid, but her critics are, because she's not hurting anyone, other than the pain she chooses to inflict on herself to get what she wants, be it body art or an implant. A lot of people do things that give themselves pain or even injury in order to achieve a goal or participate in an activity.