What is opportunity cost neglect?

Opportunity cost neglect is a concept in personal epistemology: Every choice to do X is a choice not to do Y — consider what you give up.

Example: You decide to spend Saturday rewriting a side project in a new framework. That's 8 hours you didn't spend writing, exercising, learning a new domain, or resting. The rewrite might be the right call — but only if you've actually weighed it against what those 8 hours could have produced elsewhere. Most people never run that comparison. They evaluate the thing they're choosing in isolation, as if the hours came from nowhere.

This concept is part of Phase 23 (Decision Frameworks) in the How to Think curriculum, which builds the epistemic infrastructure for decision frameworks.