The cash tied up in simply running the business - for a DTC brand, overwhelmingly inventory: pipeline, on-hand and safety stock. Many brands sit at 20-30% of revenue locked in inventory at any time, and that ratio drives the growth death spiral: doubling revenue means doubling the inventory commitment before the new revenue arrives, so a brand can be profitable at every level and still be unable to fund its own growth. You cannot grow your way out of a working capital problem - the faster you grow, the more cash it swallows. The fix is structural: shorter lead times, supplier terms, and financing matched to the cycle.
Benchmark. Your inventory ratio has to be supportable by retained cash plus available financing. Quad Lock kept inventory under 15% of revenue, which is what made bootstrapped growth possible; and no single purchase order should exceed 30% of available cash.