While the income/happiness correlation does exist, it is an internal comparison rather than an external one. See for example this breakdown by country. The data suggests that people construct their notion of happiness in part comparatively to the material wealth of those around them. While this might not apply to very basic needs (i.e. people starving) it seems that this starts to have a substantial impact before all the physiological needs are met. I'm incidentally not convinced that the top tier on Maslow's pyramid is anything other than a culturally mediated set of values rather than a set of intrinsic goods. There's also a fair bit of empirical criticism of the levels of the hierarchy as a whole This is one good criticism that favors something approximating rationalism over Maslow's set. I've been told that Wahba and Bridgewell's papers in the 1970s also provide a lot of empirical evidence against Maslow although I haven't read them myself.