Stablecoin adoption has a competitor hiding in plain sight: the interest paid on bank deposits. An October 13 BIS working paper, using US data from January 2019 to June 2025, finds that higher deposit rates predict slower stablecoin growth. The relationship is stronger for USDC than USDT. The opportunity for stablecoin businesses depends partly on how attractive bank cash looks, not just how many wallets they reach. That doesn't prove stablecoins are draining the banking system or tell us what today's token prices should do. For investors, compare funded balances and repeat payment use with deposit-rate competition before extrapolating adoption.