One theory I have about that is that they "wear" their tattoos like clothing, or hair… and without them, they feel naked or bald.
Another theory I have is that even if they do regret them, they never admit it.

There are some tattoos that are just a bad idea.. for instance... getting the name of a girlfriend or boyfriend tattooed on one's body...
and then when that relationship ends.. the new girlfriend or boyfriend is not too enamored with that tattoo. 
One extremely attractive cam performer got a huge tattoo of his mother's face tattooed on his chest.  It covered half his chest! The face
looked very creepy, not pleasant at all.  He turned off just about all his fans with that tattoo.
I knew this straight guy who had the names of several guys tattooed all over his body.  I'm not sure why he did this.. but my guess is
those were young men that he knew who died in the military.  But.. I think that has caused problems for him.. because no girl seems
to want to have anything to do with him even though he is quite tall and handsome and friendly.  I found his facebook page, and he was
ecstatic when he finally got a girlfriend.  He was head over heels in love with her.. but.. that facebook page tells a story, because a few
months after announcing his relationship with her and posting photos of them together.. there are no new photos of her, and it has been
years since then, and no NEW girlfriend.  Pretty sad.

Lastly, when one has visible tattoos on their body, it handicaps their job opportunities.  For instance, getting a job in a restaurant as a server, or in a theme park.