Humans socialize by relativity, which gives them a sense of belonging to a group, an interest, or a lifestyle. For example, you would be more likely to be friends with a similar taste in music, as opposed to one who does not. While human interactions and social networking differ on several different scales, this is one theory that is fairly solid.
Having said that, there are also several other factors to take into account when socializing - demographic, personal beliefs and principles, language barriers, etc. When two people share a strong relativity to a certain entity - let's say, their favorite band - they might become the best of friends, provided that other elements of themselves are compatible, and if not, whether or not they are willing to compromise and tolerate certain traits of each other that might not necessarily align with their own.
Now, I'm known to be someone who really likes tattoos and have some knowledge about the local tattoo scene. I offer my limited knowledge wherever I can to peers or people I know who have questions. Most of the accounts I follow on Instagram, Tumblr, and Facebook are somewhat related to tattoos.
My company recently recruited a new member of staff, who happens to be a girl, who also happens to have an interest in tattoos, which is cool - as it is, our company is a dry desert with almost no girls, so a girl who has a similar interest as mine (relativity), all the better.
My superiors emphasized this point to me: that she was also a girl who emphasizes her embrace of tattoos, and that I would get along well with her.
While I have several friends and acquaintances with whom I share interests with, there are also several people who share mutual interests with me that either do not like me, are not liked by me, mutually hate each other, or we just do not speak. For example, I know guys who have tattoos who hate my guts because "girls are not supposed to have tattoos"; I know people who have tattoos whom I cannot/don't get along with either because we don't go with the same crowd, or our personalities limit our communication.
It was like how my parents expected me to get along with a family friend's daughter, who's around the same age as I am. I didn't get along with her, but ironically, my younger sister did. Whether it was the social awkwardness that plagues my social life, or that we just couldn't get along, I don't know. Not that we hated each other - I just didn't have much to say to her.
Tattoos and the industry itself is marvelous, and it's a really great thing to bring people together to share aesthetic opinions, broadening the spectrum of art styles within the industry, and just fawning over awesome needlework in general.
It does not, however, guarantee that anyone would get along with anyone else who has an interest in tattoos.
Some people get tattoos purely for the aesthetic value. Some get them for attention. Some get them as a memento of a life event. Regardless of the reason that one gets a tattoo, it's not "wrong" if it's by an artist who knows what they're doing.
I avoid "regretting" a tattoo by making sure they have substantial meaning before I go ahead to even research who does the best in the style I'm looking for. Apart from being a little skeptical of those who get tattoos just for the sake of getting them (without knowing what they want or what they derive from the tattoo), or opting only within the range of Pinterest/Tumblr tattoos, I respect everyone's objective of getting any tattoos, even if I quietly judge shitty tattoo choices/placement.
But apart from our interest in body art, our core beliefs may differ. Our lifestyles may differ. These differences may dictate whether or not we get along well. Our interests only serve as a potential catalyst to becoming acquaintances, let alone friends.