This study investigated people's willingness to prioritize social well-being and trade-offs between fairness and personal well-being through a stated preference experiment with a representative UK sample (n=300). We estimated individual-level utility functions using the expected utility maximization (EUM) framework and tested their sensitivity to small-probability overestimation using cumulative prospect theory (CPT). The majority of participants exhibited concave (risk-averse) utility curves and a stronger aversion to inequality in social life satisfaction outcomes than to personal risk. These preferences were independent of political stance, suggesting a shared normative stance on fairness in well-being that transcends ideological boundaries. The findings raise concerns about the use of average life satisfaction as a policy indicator and support the development of nonlinear utility-based alternatives that more accurately reflect collective human values. We discuss Takeaways for public policy, well-being measurement, and the design of value-aligned AI systems.