$imple - I can certainly understand your perspective and it is valid to wonder about how someone would do this.
I personally think it is akin to wearing earrings or other jewelry, but being permanent it requires no attention, and won't set of a metal detector
I waited until I was 30 before I got any tattoos, and I am glad I did. Now my tattoos have meaning and represent a certain time in my life. I know when I am a shriveled old woman the tatoos are going to look pretty silly, but it will reflect who I was/am.