Tattoos & aging is a subject that has no definitive answer right now. While the inks used today are different than those from decades ago, there are no long term studies to say what they will look like in a few decades, or if they will hold up any better. A good Tattoo artist will tell you that, if they are honest. It's nothing more than an assumption to say they won't look just like the blue blurs seen today on many care home residents who got a tattoo 40+ years ago.
Tattoo.com Q&A on aging
Weight Loss/gain also obviously affects them, and since few people remain exactly the same weight and same build for their entire life, it's also a consideration.
Tattoo.com Q&A on Weight & Tattoos
Personally, I have none & won't be getting any - but to each their own.