Worst that can happen? If banks have used peoples' savings to purchase Evergrande debt or anything related then the banks may not get repaid which would result in the banks losing peoples' money leading to people spending less money resulting in a recession or depression.
Instead of default the bad debt and a recession, what alternative is there? Prop it up a little longer? Default on everything, go to CBDC, and issue everyone monthly CBDC tokens to buy food?