I'm pretty embarrassed with what I'm about to post but thought it was worth saying. Sorry for the lack of organization this is my first post.

STORY

I was very much into cuckold porn with my two ex girlfriends. (I dumped one and immediately started it up with the second). I was a pretty passive guy and although on paper I had far more SMV than both of them, I was extremely needy because I needed a girl in my life to validate myself. So while at first they were in head over hells in love with me and in both cases initiated the relationship, through both relationships all of it was lost as well as their respect for me. I even told them my fantasy during dirty talk in bed.
After my "fantasy" came true against my will and she (the second gf) cheated on me with another guy with a big dick I lost my mind. I would have panic attacks whenever I saw them (him or my ex) in person or through facebook, anything that reminded me of them or even their names my mind would race and my hands would shake and I couldn't form complete sentences or focus on anything. I would breakdown and cry, but not in a release almost out of frustration and fear as I had no idea what was going on. I couldn't sleep without multiple nightmares waking me up and would not eat as hunger would ease my condition. I started abusing substances like alcohol and then adderall to cope. I toyed with the idea of suicide multiple times, but was too much of a coward to go through with it. I don't want to undermine veterans since I didn't go through anything half as bad as war but it was similar to PTSD symptoms.

While this was going on I searched for answers and everyone gave me bullshit "you'll be fine" and "she's just crazy" which I knew was bullshit. I started to realize a lot of the The Red Pill lessons before I found this site, and eventually found it helping me better understand all of it. While it sucked I started pursuing my own goals and to become the man I always wanted to be but had previously accepted as impossible. I began working my ass off and trying my hardest to better myself. Fucked a few girls and didn't grow attachment to them (for the first time ever). While I'm a lot less "beta" now if you want to call it that. I'm nowhere near where I need to be but on my way for sure. Somewhere along the line a weird thing happened. Cuckold porn just stopped turning me on. At first I would watch it and imagine myself being the "bull" or the one fucking the girl and then one day I went on /r/cuckold and was so fucking confused why it ever turned me on. When it happened I didn't think much of it and just jerked off to something else. Looking back though, that was probably just the external symptom of other changes I made in my life.

THEORY

The panic attacks were because men are naturally not supposed to be betas. Or maybe just not me personally. While I toyed with the idea of accepting this submissive role in the fantasy, my mind could not accept the realization of the role and refused it like an illness. Any reality that suggested it was vommitted out que the panic attacks.

I was into it because the relationship made me content. It was like saying, this girl makes you happy and you will never get a better girl than her or ever be better yourself so be happy. Who you are now is who you are forever.

My natural masculine drive to better myself was neutered by me 1. Drawing validation from this girl and 2. Me thinking that this was the best I could get and accepting mediocracy. So for me, this girl was the most validation I'd ever get, so the only way to increase that validation would be let her fuck other guys "simulating" the thrill of the chase, increasing her value and my validation. I'll put this another way:

A lot of guys into cuckolding porn might have high SMV in a lot of ways (good looking, workout, high paying jobs) but they are beta in the fact that they have committed to a women in fear they will never find anyone else or can't do better (out of scarcity). That desperation is the core of the "turn on" of the porn. For these men the majority if not all of the validation in their LIFE comes from ONE GIRL. That's why they'll often buy them everything they want and focus their life on giving them everything. This may seem selfless, but in reality it is to increase her value and thus his validation. Eventually there is a limit to the amount of material things he can give, insert cuckolding.

Cuckold porn is basically a pretend scenario of the idea that the one girl that'll ever love you might leave you forever for someone better. This raises her value while destroying yours. But you don't give a shit about your own value because your validation comes from her... That's why its so "hot".

As you can imagine and if you do a little research, in MANY cases women leave their sissy husband for their bull. As their husbands value plummets, they jump ship.

TLDR: Cuckolding is due to scarcity.