heyya! I'm reading through your posts and I'm growing more and more confused about c!dream (like trying to put a puzzle together without knowing what it looks like at the end). Basically, I get that he built the prison for himself and had c!punz throw him in, but why would he do that? /gen
well!! to be honest, we don't know for sure bc c!dream is a bitch and rarely states his true intentions (or "reserved" as cc!dream likes to put it). it's all pretty theoretical at this point.
/rp
but!! we do know the end goal of dream's plan. his motives. he wants the server to be back to like what it was before (pointedly before tommy/wilbur/l'manburg arrived), without factions, war, etc. his way of getting there seems to be, so far, making himself public enemy #1 so the server will come together (as a community, as a "big happy family") and take him down. he's the self-sacrificing type, even if it doesn't seem like it, because all the distancing he's done and the actions he's taken leave him out of the family he's hoping to make.
he probably thought people were going to want him dead at the climax of the disc finally, hence the prison (think back to all of dream's comments on "It’s just an option because if you can’t kill somebody, you might need to lock them up.” (thank you @call-me-apple's lore doc which may help you do some digging of your own)). he wants to see his plan though, so he's not going to let himself die, but people also need to feel like they won, y'know?
as for punz. it wasn't specifically punz that put dream in the prison, but punz did lead the server to dream and has a pretty public "betrayal" so i get what you're saying. that! was to protect punz ("you should, but you should act like you’re not on my side. because if you’re on my side then you’ll be in danger..."). dream cares very deeply about his allies and he protects them. you can see that with punz, techno, etc. he feels solely responsible for the server so he's not gonna be sacrificing his only allies left and right, y'know? he thinks a LOT about what they're doing and how he's going to use them. he's very mindful with his friends, even to an unhealthy level.
so.... long story short, nobody knows what's really going on besides dream, punz, ew!ranboo, and maybe techno. all we know is its a part of The Plan(tm) as remarked by punz after meeting up with dream. it might've been to keep him from being killed so he could see out the end of his plan, preparation time (such as other theories suggest), or whatever the hell dream has cooked up in his incredibly unstable tunnel vision. it wasn't supposed to go the way it did but uh. it was Supposed To Happen, so that's something i guess.
uh anyone is free to add to this post we need to hold hands like little kids in this dark abyss