If headlines were enough to profit, why do so many traders still lose money?

I’ve been reading a lot of threads here, and a big portion of the discussion seems to revolve around headlines/news and “what do I do now?” That made me think about a question we rarely ask directly: What is a stock, in practice? It’s not the news. It’s a price that reflects collective expectations about future cash flows, risk, and sentiment and those expectations update continuously. News can absolutely matter, but reacting to headlines alone often isn’t a repeatable approach because: information is frequently priced quickly, the interpretation (and what’s already expected) matters more than the headline, and results are often dominated by process rather than “having the right info.” Where I’ve seen the biggest difference is having a clear framework that answers: Thesis: what do I believe and what would change my mind? Valuation / expectations: what needs to go right for this price to be justified? Time horizon: is this a 3-month view or a 3 year view? Risk: what’s the downside case and how do I avoid a permanent loss? Position sizing: even if I’m wrong, can I stay in the game? I’m not claiming this is the only way to think about it just sharing a lens that helps me separate noise from signal. Question for the community: When a big news item hits, what determines whether you change your thesis versus do nothing? What’s your decision rule?