“There's some great use cases for TAM, the big one being really like a sales tactic to be candid. From a TAM standpoint you're going out to investors talking about how big the opportunity is. The flaws come when you start trying to calculate the addressable audience from a modeling standpoint and what you should do strategically from product strategy and monetization strategy.”

TAM is a sales tactic — SAM is what should drive strategy

Use TAM for the investor pitch and the dream. The moment you use it to model product or monetization strategy, you'll be wrong. Operationally, you want SAM — the serviceable addressable market that actually reflects who can and will pay.