(I am massively generalising here, no offense is intended, I know this doesn't fit everyone)
I see it more like a slippery slope of shame and being in-denial.
I think people look at people further down the slope and feel some justification about their situation because they're not as far down the slope as those others and feel like they never will be. Where they are is a reasonable limit, any further would be shameful.
Meanwhile, thoughts about the things people further down the slope do eat away at them and tempt them further down the slope. It might start only when they are peak horny, like involuntary fantasies as they are about to cum. They'll brush it off and try not to dwell on it. Eventually those involuntary fantasies become more regular, it feels especially good to indulge in thinking about them and they become semi-voluntary fantasies.
At some point the denial reaches a breaking point, they give in and accept they've slipped further, they feel shame but with it comes great pleasure.
To give examples, there are guys that are turned on by the thought of their wives with other men. They may have wrestled with that notion or maybe not but they come to the conclusion that they might like to try an mfm threesome or swinging. They'll find a way to justify that it's just extra pleasure for them, they're not missing out on anything and their wife will enjoy it equally. They've probably heard about hotwifing but consider that to be the wife having her cake and eating it, they don't see that they should miss out on participating.
At some point they may find themselves mesmerised by watching their wife getting fucked, their focus will eventually shift to that until they are essentially hotwifing. At this point they justify it that they're still equal to (not submissive to) their wife, they just enjoy seeing the pleasure she gets from other guys. When they hear about cuckolding, they might dismiss it as men who have bi tendencies and claim they don't enjoy humiliation but they see humiliation as being verbal degradation.
Their hotwifing might lead to enjoying sloppy seconds but that's ok because they don't think of it as another man's cum, it's just their wife's extra warm and wet pussy. They might choose more and more dominant men with bigger cocks, this isn't humiliation, it's just because they enjoy seeing how much more pleasure their wife gets from it. They might get the urge to take part in fucklicking, but again, it's not humiliation or submission, they're just getting closer to the action.
The wife might start to take control of who she sees but this is just hot to see her so keen to enjoy his fantasy. She might choose to see guys that aren't interested in having her husband around. Feeling left out they might like to prepare the wife for her dates, this isn't submissive, this is just sharing the experience with her. When she returns, they'll want to hear all about her lover's prowess, how big his cock was, how long he lasted, how hard he fucked her, how many times he filled her with cum. This isn't humiliation, he just enjoys sharing her experience. These stories might be told while she strokes his cock but over time 69 might become more satisfying until the point where she comes home and jumps straight on his face while she tells him all about it but its ok because she showered, absolutely no cum survives the shower.
Sometimes the thought of her being full of cum enters his mind while he's going down on her and makes it hotter, if she's stroking his cock when he thinks about it he'll shoot his load but he would never eat a creampie for real, that'd be bi/gross.
One day she comes home unshowered, they lay on the bed and she reveals some details of her encounter before she heads to the shower but he gets horny, she can sense that he's tempted to go down on her unshowered, the idea turns her on too, she squats over his face jokingly, he protests but she now can't resist the urge and forces her pussy against his mouth, she grabs his head and he instinctively licks her pussy, she cums hard, forcing cum into his mouth. This was just a moment of weakness, there probably wasn't any actual cum, that was probably all absorbed on the journey home. She wasn't humiliating him or asserting dominance, it was just some fooling around.
One day after watching a hung stud empty his balls into his wife, she beckons him over, he finds himself going over to her, he looks at her, legs spread, freshly fucked pussy, cum seeping out of her, she doesn't have to say anything, he knows what to do.
Ok, this got out of hand, it wasn't my intention to write all that, it was supposed to just be a couple of examples. I don't half write some shit sometimes
and it annoys me that I changed from "they" to "he" at some point
ah, whatever, I'll leave it in.
Anyway... I think this applies to most forms of submission.
I'm sure people will remember girls back when they were virgins claim that they would never suck a cock or never sleep with a guy they weren't in a relationship with or sleep with a guy on a first date etc. Any girl that would do those things is a slut. Most end up slipping down the slope and it's enjoyable for everyone involved.
My wife was one of those that claimed she would never suck a cock, she didn't with her previous 6 boyfriends and claimed she never would and would never want to, "it's gross and animalistic, girls don't actually enjoy it, they just do it to please the guy".
Watching her give into that newly experienced urge with me and swallowing before heading back to her boyfriend was one of my hottest moments.
