Since you seem incredibly confused about both how to argue and basic facts about reality, let me walk you through this.
You claimed that purchasing meat has no effect on whether more meat gets produced, because “they make their own decisions.” This argument rests on the completely insane premise that paying people to do things does not influence their behavior or make you complicit when they decide to do what you paid them to do. If this were true, it would lead to the absurd conclusion that hiring a hitman to kill someone would not make you complicit in the act, because, by your logic “they make their own decisions” regardless of who’s paying them to do what.
If you want to dispute that, you have to actually find a fault in that chain of reasoning, not just say, “Nuh uh” over and over again.
An argument’s a collective series of statements to establish a definite proposition. Contradiction’s just the automatic gainsaying of anything the other person says.