APT Margin Transaction Losses, page-19

You are making assumptions on the credit worthiness of Afterpay users... Which is odd because there is actually specific research information out there on the credit quality of users and this research might surprise you (although it sounds like you're not a huge fan of research, when speculation is much easier).

Have a look at "How millenials manage money" report (make sure you graph the PDF). Afterpay users earn more money than non-afterpay users and are more budget savy. The 1% default rate (and no rise during COVID-19) also contradicts your statement.