WeChat has 1.2 billion users. Massive user data makes it easy to test products. 
The WeChat company relies on the WeChat payment method to survive, charging merchants a 0.2% handling fee. 

Ordinary users will be charged a 1% handling fee if they withdraw change from WeChat. 

The personal code does not charge any fees, but it only supports change payment and red envelope issuance. 

It does not support credit card binding payment methods, but the merchant code does support credit card payment methods and charges a 0.2% service fee. 

WeChat companies survive by collecting fees from WeChat Pay. Handling fees are charged 24 hours a day. 
A very profitable mobile payment platform.