The calm week is the wrong model

Why does a stress scenario shock every risk sleeve at the same time?

• To keep the arithmetic simple
• Because in crash weeks risk assets tend to fall together, whatever they did in calm weeks
• Because every coin always falls by the same percentage

Which of these counts as spendable reserve in a week when your lending market is fully borrowed?

• Stablecoin sitting in your own wallet
• Stablecoin you supplied to that lending market
• Bitcoin, if you are willing to sell it at any price