I think beyond penis size, its definitely a mind set first being or wanting to become a cuck. But if you have a small cock, or PE issues, or like me, both of those, there isn't a whole lot out there for you. So becoming a cuck, gives you something to belong to, a tribe, where you realise you're not the only one out there. Its also turning lemons into lemonade for small dicked guys like myself, where you get to turn a lot of negative thoughts and emotions into something thats highly sexually charged. Its a masochistic desire being a cuck, but its also the gift that keeps on giving, once your masturbation habits follow that path.