On the other hand, who is making money in this transaction? How much money did you make?

According to the analysis, it is a normal transaction for Master Wang to enter the shoes, and it is also a normal transaction between Master Wang and his neighbors, that is, there is no wrong transaction between them, which leads to one party making money. Master Wang spent 30 yuan but got a pair of shoes. He took 50 yuan from his neighbor and returned it to 50 yuan. Therefore, when Master Wang entered the shoes and the transactions between Master Wang and his neighbors were in a state of neither profit nor loss.

Conversely, let's look at the transaction between Master Wang and the customer. The customer took a pair of shoes bought by Master Wang 30 yuan. Because of the sale, this pair of shoes was priced at 20, and was given to Master Wang for 50 (fake money, equivalent to no money), and Master Wang got his 30 yuan back. So the actual loss of Master Wang includes a pair of shoes (30)+30=60.