You've identified a correlation. What solipsism is objecting to ("big claim"/"hypothesis") is the statement "There's a reason for that", which implies that the

You've identified a correlation. What solipsism is objecting to ("big claim"/"hypothesis") is the statement "There's a reason for that", which implies that there's a causal relationship between the prevalence of haggling and countries being "backwards and economic disasters" (for which there's been no evidence provided).