No, being otherkin in itself is not about being in a cult. The circle triangle thing is just a symbol some people like to wear to subtly signify they they're a therian. It's much less noticeable than a tail.
However, there are those out there who will be happy to take advantage of young and vulnerable people who come their way. We often tell newer members a few things to try to steer them away from being taken advantage of such as:
1. No one else can tell you who you are. If someone is trying to tell you what your kintype is, or who you were in a past life, or what you should be doing in this life, they're probably full of it. Be very wary of people like that. By claiming to have such personal information about you they're also gaining, or trying to gain, a measure of control over you. Claiming to have shared a past life together is prime territory for this. Keep your own notes and keep them private so they can't play off of what you've told them. Keep track of what they've told you and see if the story has changed over time. Though honestly, if you find the need to keep such notes you should have heeded your instincts and gotten out of there already.
2. Physical shifting is not real. Some of these cult-like groups claim that they have some kind of magical secret that can make you physically more like your kintype. Wishing really hard and increasing the strength of your phantom shifts is never going to get you there. If it worked, more people would be doing it. In thirty years of being otherkin I have never seen a single shred of evidence indicating that this can happen.
3. Be Wary of Packs and Pack Leaders. Some people use the outdated concept of wolf hierarchy to make themselves look and feel important. If you're in a pack that puts a lot of emphasis on ranks, then you might want to take a serious look at those leaders. Do they snap when someone disagrees with them? Do they make all the decisions? Are there any subjects that you simply don't talk about because it will upset the alphas? (This is not wolf exclusive, similar groups can form around any shared kintype or experience.) This forum does not allow pack advertising for a good reason.
*Honorable mention* There are no such thing as otherkin hunters. The government has no interest in you, because of #2 above. You're simply not worth hunting. If your friends are telling you this then they may be trying to use fear tactics to get you to do what they say. Or they're just bored and looking for excitement.
Young otherkin can be especially vulnerable to these kinds of things because everything seems new and mysterious when you first start out. Being different from others around you is an alienating experience and you might be tempted to latch on to the first people who give you a sense of belonging. It can be hard to give up that social comfort when faced with a situation that is less than ideal. Species dysphoria can be very disturbing and anything that promises relief and escape can also be very tempting. Your best bet is to join an established and experienced community that doesn't put much emphasis on rank, like this one. You won't get shiny promises here, but you will find people willing to listen to you and to offer friendly advice.
