Bold economic and futuristic assumptions remain taken for granted within the sustainability discourse and the Sustainable Development Agenda (SDA). This essay critically analyses these assumptions to propose a more nuanced standpoint. The analysis is embedded in an analytical framework drawn from the principles of conservation of energy or matter, protection motivation theory, and utilitarianist standpoint to interrogate, alongside current sustainability discourses, two core case studies: Polanyi and Daly. Interrogating biases and futuristic illusions suggests that SDA could be re-conceptualized with an end of improvement: here, socio-ecological resources are considered a given, while the social and qualitative ones are variable. Moreover, within the embedded analytical framework, it is noted as convincing to focus sustainability or SDA on the economic replenishment of the present rather than on vague future kinds whose needs are unknown. Yet, the challenge lies in an appropriate knowledge paradigm towards improvement as the end for sustainability or the SDA and how to advance political commitment to shift to such a paradigm.