Learn

Ten topics. Read in order or by what you need.

Each topic assumes you already know the definition. We start where the textbook stops: real numbers, real edge cases, real math.

Budgeting

Zero-based, envelope, and 50/30/20, plus the math behind paying yourself first.

Expense ratios, the Sharpe ratio, DCA vs lump sum, sequence-of-returns risk.

Exact FICO weights, the daily-periodic-rate math, snowball vs avalanche.

Marginal vs effective rates, 2025 brackets worked out, Roth break-even.

How banks earn net interest margin, FDIC mechanics, ACH vs wire vs RTP.

Unit economics: CAC, LTV, gross vs contribution margin, the cash-flow trap.

Opportunity cost as a daily lens, hedonic adaptation, expected value bets.

PITI, amortization, the rent-vs-buy breakeven, closing costs, and what a house really costs to hold.

Term vs whole life, the deductible math, which policies to buy and which to skip.

What Bitcoin actually is, volatility and position sizing, custody, and the tax rules nobody mentions.