A good thought I must say . Yes , this is very true. Just the way currency is a form of exchange , happiness too is a form of sharing . But there hasn't been yet a single type currency that is widely used all over the world. But happiness on the other hand is so contagious and acceptable , that nobody refuses to receive it or spread it across when he or she has it . Hence, I feel happiness is not just equivalent to national currency but is a form of international currency .
I really appreciate the question, rather this status posted by you . Well done .