He also emphasized that hobbies are clearly exempt from this rule. “If I want to learn to scuba dive, for example, because I think it’s fun, and people won’t pay me to do that, I don’t care, I’m going to do it anyway,” he said. But when it comes to decisions affecting your core career, money remains an effective judge of value. “If you’re struggling to raise money for an idea, or are thinking that you will support your idea with unrelated work, then you need to rethink the idea.”