The simplest durable lesson here is this: small recurring costs matter because compounding also works against you. Three quick checks before you act: 1. Name the mechanism in plain English: Investors usually notice big drawdowns quickly. Fee drag is quieter, but it compounds for much longer. 2. Say why it matters for behavior or portfolio decisions: That is why cost discipline is not cosmetic. It is part of return discipline. 3. Set the review question: Explain in one sentence what problem this idea solves and what problem it does not solve. In real life: A strategy that beats by a little before fees can become mediocre after years of friction. Common slip: The mistake is comparing products only on recent return and ignoring what must be paid every year to keep them. That is usually where the edge is: not in the vocabulary, but in the structure underneath it.