Bank of America pays you about $2 a year on a $20,000 savings account. A money market fund pays $800. Sarah's "Friction" essay just explained why they get away with it. Most people never get around to moving the money, and the bank built a fortune on that. And she's inside the machine she's describing. She structures private credit deals for a living, reads about rates every day, and her own cash is still sitting in a zero-interest account while her relationship manager emails her about it. If…