After Hide & Seek, I found that many Os still staying quite unrealistic, with the prize being 1.7b and especially looking at half of the actors portraying them. So I thought why not make a guess on why they chose to stay. This is based on what their actors portrayed them on screen.

039 - Fear. Knew Os were majority so switching would just make him a target. (Went from X to O after Lights Out.)

096 - Felt he could win more money (He's playing the game)

100 - 10 Billion Debt

125 - To spite Nam Gyu

163 - Felt she could win more (No personality shown, just served face)

192 - Ex Convict/gang member turned gambling addict (Aggressive and bald)

203 - Probably wasn't even in debt. Either willingly joined the games out of pure love for chaos and violence or former hitman turned crippling alcoholic. (His kill on 172 was too clean for any normal citizen)

260 - Jobless period followed by depression (Displayed a lot of anxiety on screen)

276 - Felt he could win more (No personality shown)

306 - Gullible and lost a lot of money from scams (Which was why he believed in 044)

312 - Gambling addict (No personality shown)

336 - Loan shark debt + trying to earn enough extra income for fresh start for his family (Family man yet still persistent to play is insane)

353 - Cryptocurrency loss (Is a teacher, so his debt must've been a sucker punch)

435 - Felt he could win more (No personality shown)

442 - Jobless cranky alcoholic & loan shark debt (Aggressive)

448 - Same with 039. And her being a female makes her an even easier target.

Os reason