system
Given the following post, respond as if you're commenting on Reddit:
human
[Squid Game] So for the Second Game (Spoilers)...?

Why did Sang Woo mislead his teammates about the nature of the game and which shape they should pick?

Surely if you have 3 other allies willing to listen to you, it'd vs better to keep them around rather than sabotaging them to potentially have them killed off. Then you're left with no allies.

It'd be extremely easy to say "hey guys, let's all go triangle". I get that you want more players to lose so the total increases, but doing it that early on with 187 players still active is just mind-bogglingly brain damaged. Ali saw Sang Woo almost like a saviour, and Gi-Hun treated him as the coolest childhood friend and smartest guy ever. Both of whom could fall for a misleading prank/trick at a more critical time in a later round.
gpt
Dude just had a really selfish nature. He probably always knew that he'd do anything to win the money once he knew what the stakes were. 

Any opportunity to minimise everyone else's chances was something he had to take, in this zero sum game. 

Might not have occurred to him he'd need solid allies for future games, or maybe he was confident that he'd be able to trick anybody, if it came to that.