I'm older than most members here (duh...) and I've considered getting a tattoo several times over the past years, but...
1. Can't get my head around the fact that once it's there you can't get rid of it (not without troublesome surgery that could leave scarring)
2. Can't imagine / don't want to imagine what it might look like when I'm really old and wrinkly (even more wrinkly than now...)
3. Never liked anything or any word / visual/ graphic symbol enough or long enough to want it permanently inked onto my body - I mean, what if I change my mind about how cool something is and next year I really dislike it...?
I don't care about pain or needles and I guess infections are just unlucky or a question of making sure the tattoo parlour/artist is professional.