You've been marked as a troll, but I don't really think that's fair. Not everyone wants a tattoo or understands the tattoos that other people get.
I know these things are going to be on my arms for the rest of my life. And when I wake up in the morning and look at them, I think, "these are the arms I should've been born with".
First of all, you have to understand that not all tattoos are created equal. I paid $150/hr for mine. I looked for a long time for an artist whose style I liked, and when we sat down and did them, it took a really long time. All tattoos fade and bleed a bit, but good artists will know how to handle that a little. But hey, when I'm 80, I'm gonna be a little faded and fuzzy around the edges too.
My sleeves are thematic--I was born in the year of the Snake, in a fire cycle. I already had the words for 'fire' and 'snake' tattooed each on one wrist. My right arm is a red and black snake wrapped around bamboo with clouds, and my left arm is a blue, slick snake on a backdrop of flames and smoke. (Their mouths are closed, and they look quite happy--I firmly believe you need to be able to talk or fight your way out of any tattoo you have, and I dislike aggressive snakes for myself, because I'm not going to want to fight my way out of anything.)
Anyway, my tattoos are just a way for me to feel closer to part of my culture. They're a pretty bit of art that I get to carry around with me. They look good with the clothes I wear, like any accessory. That's what I wanted out of them, and that's what I got.
Other people have other reasons, but those are mine. :)