GDP matters because resources matter, but it is only one instrument. A country can be rich and still make ordinary intent hard to fulfill.
If people cannot afford a home, trust the rules, raise children, start useful work, breathe clean air, or recover from mistakes, the national operating system is wasting life.
Fulfillment is the quality of the environment around action.
The better question is not "Which country is richest?" It is "Which country makes good intent easiest to translate into lived value?" That question brings economics, culture, tools, institutions, and place into one frame.