You're conflating financial value and the abstract concept of value. Financial value is really just a function of supply and demand. Food and clean water may be

You're conflating financial value and the abstract concept of value. Financial value is really just a function of supply and demand. Food and clean water may be a lot more important than megayachts, but they're also also far more abundant than megayachts. It happens that maximizing financial value also does a good job of improving people's lives, so we treat as truth. Right now, we're starting to see this fall apart as certain valuations stop making sense and certain negative externalities start coming to light. That said, I still think in general, valuations tend to be more right than they are wrong.