While it is true that the interest earned from depositing 1 million yen will be only 10 yen, we need to consider since when and why deposit interest rates have become so low.
The finding that people in rich countries don’t report much greater happiness than those in lower-income countries – even though, in any given country, the rich say they are happier than the poor do – is called the Easterlin paradox, after its discoverer.