I don't think that $75k was to live comfortably, I think the $75k was to feel happy about your income.
Ninja edit: found it:
...Daniel Kahneman, who in 2010 published an influential study with fellow Nobel Prize-winner Angus Deaton. The 2010 study found that money could only boost happiness up to a point — about $75,000 in annual earnings. Beyond that figure, the researchers concluded, money had little impact.
but...
Now, new research from a Nobel Prize-winning economist and fellow researchers provides a fresh answer. Money does appear to boost happiness — at least for most people — up to earnings of $500,000, according to the new paper published in this month in the Proceedings of the National Academy of Sciences journal.