wait

Correct me if I’m wrong but he did remove Doha’s tapes and probably some of the other players tapes, so they all lose their memories. I think he believed that only one person could leave so that’s why he remove Doha’s tape. He also got rid of Bada’s tape out of spite toward Doha. That’s as far as I can remember.

Ur correct that he did remove tapes but only Doha's. All the other players (Hyungshin, Jae-seob, Young-taek) removed their tapes willingly bcoz of the endless game. Seongchan & Doha were the only ones left until they made Bada (NPC) a player. Bada was good at the game and Doha tracked their progress. Then Seongchan was afraid that only 1 player would escape if the game ends and removed Doha's tape. He also stabbed Bada & removed his tape to spite Doha so really Seongchan has beef on Doha XD

Not only Doha's tape, but also Bada's at one point he was taking it out and putting it in corrupting data or giving bada multiple tapes making him forget the other rounds. Also tricking Bada this way to think he was the only player while others were npcs, having his tape playing in the bg all the time and pretending to be npc himself so Bada completes the whole game so he can have an easy escape, leaving everyone behind.
I might have mixed up some facts but I think he did something along this lines. Anyways his a manipiulitive piece of shit.

Well, the list is real long, but basically what I think we can surmise from this fucking storage place full of tapes, is that Seongchan in that moment decided the key to him winning was manipulating others' memories through those saves.

It might be true that Jaeseob and Hyungshin gave up voluntarily, but it might also be true that that's the bs Seongchan fed the others, according to the newest chapters. He for sure has manipulated people by hiding their tapes and given them the wrong information many times while he takes the easiest way out.

If you read the latest chapters, it was revealed SC also removed HS's and JS's tapes against their will