Okay, so if I am understanding what you have asked, there seems to be 2 or 3 separate questions here.
1) Why do people engage in BDSM activity?

This is difficult at best to answer with a general sweep of a broad brush. It’s really easy for me to sit here and tell you that people often have
something like a job, or responsibility in their lives, and being a submissive is a way to simply let / allow someone else to take control. Now, to be sure. There are people like this. NO ARGUMENT; however, if I’m going to be honest, I have to tell you to answer this question is like asking 10 different people how to make a cake. Chance are better then excellent you will get 42 different recipes, or in this case 42 different answers. Sadly, all of them would be good, and I would clearly hesitate to speak for other people, especially without their permission.

What I can tell you is there is a bond, a special trust that MUST exist between Dom and sub especially if the relationship is going to succeed. That trust is both therapeutic and beneficial to both participants. Not to forget to mention it’s also enjoyable. That being said, it’s here that I tell you that different people derive their enjoyment in just as many different ways. Some love the physical enjoyment of the orgasm. Some people love the security of having someone trusting them. While still others get
their enjoyment from the process. The “What’s going to happen next?” feeling, or the associated possible feeling of embarrassment if they get caught. I might at this point also tell you that people may choose to engage in BDSM as a means of connecting with the past. In history Man protected “his woman” and the woman served “her Man”. That feeling of being protected and of providing of one you like is still present in BDSM today.

2) Is BDSM connected to childhood experiences?

The Nature versus Nurture thing has been going round and round for many decades. Sadly there is no easy, clear cut and dried answer here. For whatever it’s worth, I think it’s some unknown combination of both and/or neither of these things. Another aspect that is more easily considered today then before is there are a good many submissives who have been raped, or in some way abused before entering BDSM activity. But again
each seem to have their own personal reasons as to why. You mention your trauma, and wanting to smack the crap out of people. First and really important to understand. That is NOT what BDSM is about. Smacking someone is certainly NOT ALL there to BDSM. Today BDSM is about sharing fantasies. In real life, or online. These fascinations are as various
and as numerous as there are people. Some men only like white women. Some women only like having their bodies massaged all over. Yes, to be sure there are far more extreme fascinations; however, so long as it is
safe, sane consensual, and FUN for the participants. There is no problem.

3) Are there people engaged in BDSM who don’t know What they are, or should be doing?

Clearly and resoundingly. YES! YES! YES! The major problem here is people watch things on the internet, or on Television, or they read something in a book or magazine. Then they assume they can do what they see, or read. What has NOT been taken into consideration is there are such things as make up, special effects, editing, and people who write fiction. Also, people in movies have training, and practice. They have other people helping them behind the scenes. As a submissive woman, I can not tell you how many times I have been asked to walk on someone’s chest with 6 inch stilletto heels. Can you say punctured lung? OoucCCH! Unfortunately, there are also idiots out there that want to teke unfair advantage of a situation, and once a submissive is tied up they bring out a lead pipe, or bull whip, or some other major implement of pure torture not agreed to by the submissive. On the flip side of this is a sub who will play then falsely accuse a Dom of rape. Gee Thanks a hell of a LOT!