The rapid expansion of generative artificial intelligence (Gen-AI) is propelled by its perceived benefits, significant advancements in computing efficiency, corporate consolidation of artificial intelligence innovation and capability, and limited regulatory oversight. As with many large-scale technology-induced shifts, the current trajectory of Gen-AI, characterized by relentless demand, neglects consideration of negative effects alongside expected benefits. This incomplete cost calculation promotes unchecked growth and a risk of unjustified techno-optimism with potential environmental consequences, including expanding demand for computing power, larger carbon footprints, shifts in patterns of electricity demand, and an accelerated depletion of natural resources. This prompts an evaluation of our currently unsustainable approach toward Gen-AI’s development, underlining the importance of assessing technological advancement alongside the resulting social and environmental impacts. Presently, efforts to boost computing sustainability largely focus on efficiency improvements, including enhancing hardware energy efficiency, refining artificial intelligence algorithms, and improving the carbon efficiency of executing computing workloads through spatiotemporal workload shifting. In the presence of relentless demand and prioritization of economic growth, this siloed focus on efficiency improvements results instead in increased adoption without fundamentally considering the vast sustainability implications of Gen-AI. We argue that responsible development of Gen-AI requires a focus on sustainability beyond only efficiency improvements and necessitates benefit–cost evaluation frameworks that encourage (or require) Gen-AI to develop in ways that support social and environmental sustainability goals alongside economic opportunity. However, a comprehensive value consideration is complex and requires detailed analysis, coordination, innovation, and adoption across diverse stakeholders. Engaging stakeholders, including technical and sociotechnical experts, corporate entities, policymakers, and civil society, in a benefit–cost analysis would foster development in directions that are most urgent and impactful while also reducing unsustainable practices.