For most people, more money does in fact correlate strongly with more happiness. Who is the audience of this piece?
If I think of the people I know who are happy and unhappy, money isn't a great correlation factor, and I know people are borderline homeless through to millionaires - I know happy/unhappy people across capital worth and income spectrum.
A better correlation for happiness is attitude and gratitude and enjoying the small things - the very things the article references.