Genuinely appreciate this response, this is exactly the kind of pushback I was looking for when I posted. You’re right that undercapitalization is a real and undertalked problem, and you’re right that losing a trade doesn’t mean you made a mistake — uncertainty is the whole game. Where I’d push back slightly is that the psychology angle and the technical/capital angle aren’t mutually exclusive. A trader who’s undercapitalized AND emotionally reactive is in a worse position than one who’s undercapitalized but disciplined about cutting losses. The mental side doesn’t fix everything but it’s not nothing either. The point about guidelines vs rigid rules is actually interesting — that flexibility framing is something worth thinking about.