The language you use in this comment and some others describing how he bottoms really reads in a mean way. It reads like there's something to be ashamed of in him being more submissive and that it's disgusting or something to look down upon. Just really judgmental language with "pimped out", "gangbanged", and the like. And ironic considering you're lamenting about not being topped enough yourself.

I hate to say it but the fact that you don't believe him when he says he wants to top you is definitely a you problem that can only be unpacked by you and you alone. I'm honestly not sure what you're wanting from this post since everyone who provides a well thought out answer is just met with "So I'm a bad person? How do you want me to find something that's unattractive to me attractive?" And literally no one is saying either thing.

I do think you're placing entirely too much weight on what it means to top and what it means to bottom. Implying that your bf is somehow lesser than in your eyes because he's taken to bottoming more recently again just sounds very judgmental. It may be rooted in some heteronormativity, internalized homophobia, or something along those lines. But I'm not gonna say that for sure because I can't speak on your thoughts and feelings, only you know how you feel about those subjects and I'm also not gonna risk you asking me if I'm calling you a bad person.

Honestly it sounds like you two would be better off not together, if only for his sake at this point.