Not all languages have this same word. Many use two words (or two words compressed into one such as Spanish porqué, German warum, Russian pochemu) meaning "for what reason/purpose/goal/etc.?" Anglo-Saxon hwi was the instrumental case of hwæt, "what," so it originally meant "for what purpose?" or "by what means?"
Why is there amazing human stupidity? answer: Why? We are all falling short of fulfilling our potential.
