Frictional costs

Fees, spreads and trading reduce what investors as a group can earn from the businesses they own.

2 ideas that carry it

LessonIncentivesBook
Follow the fee before you follow the advice
Before weighing advice, work out how the adviser is paid and what that pays them to say.
Evaluating any product, fund or recommendation, and in interviews about asset management economics.
From Where Are the Customers' Yachts? · Fred Schwed Jr.
FrameworkInvestingLetter located
The Gotrocks family: how helpers take a fifth of what the owners earn
Investors as a group earn what businesses earn minus what they pay to helpers; every layer of advice is a claim on that pool.
Asset management economics, the active-passive debate, and any fee discussion.
From Berkshire Hathaway's 2005 letter to shareholders · Warren Buffett