Final answer:
Scientists are pessimistic about the ability to sustain changes to happiness due to the challenges in quantifying happiness and conflicting societal priorities that favor economic growth over ecological sustainability, alongside a prevailing culture resistant to change and individual short-term interests.
Step-by-step explanation:
Scientists are pessimistic about people's ability to sustain changes to happiness due to several challenges faced in measuring happiness and the cultural practices that affect ecological sustainability. The difficulty lies in the quantification of happiness, as it is a subjective experience and cannot be measured directly. Additionally, the current societal values prioritize economic growth over ecological concerns, and there's general ignorance about the biological and ecological realities, leading to potentially disastrous outcomes. Moreover, the long-term sustainability of human society is in question, given the short-term interests and desires that typically drive human behavior, which clashes with the need for discipline in resource use and living within the planet's renewable resources.
The likelihood of achieving a cultural shift towards ecological sustainability, despite its necessity, is seen as unlikely by some scientists due to the deeply ingrained maladaptive assumptions in prevailing cultures. Furthermore, individual tendencies towards wanting more and the challenge of maintaining technological society while living on renewable resources add to their pessimism. However, it is also suggested that individuals can adopt more sustainable practices and prepare psychologically for potential future resource disruptions, which may not only inspire others but can also be personally rewarding.