Along these lines, don't the studies in your (OP's) Note 16 (to the effect that happiness is largely heritable and "unmoved by external factors") suggest that efforts to improve happiness are largely futile?

From the Lykken & Tellegen study:

"Happiness or subjective wellbeing was measured on a birth-record based sample of several thousand middle-aged twins using the Well Being (WB) scale of the Multidimensional Personality Questionnaire (MPQ). Neither socioeconomic status (SES), educational attainment, family income, marital status, nor an indicant of religious commitment could account for more than about 3% of the variance in WB. From 44% to 53% of the variance in WB, however, is associated with genetic variation. Based on the retest of smaller samples of twins after intervals of 4.5 and 10 years, we estimate that <b>the heritability of the stable component of subjective wellbeing approaches 80%.</b>" (Emphasis mine)