The growth of ‘Yes In My Back Yard’ (YIMBY) activism seems at first a simple story of a new social movement led by a new generation frustrated with the housing supply shortages created by decades of Not In My Back Yard (NIMBY) conservative spatial privilege and exclusion. Yet YIMBY/NIMBY dialectics reflect more fundamental transformations of intergenerational inequalities between past and present amidst today’s multiple scales of intensifying competition in urban life. YIMBY movements, therefore, must be understood as part of the long history of gentrification and the current, accelerating co-evolution of socio-cultural change and the circulation of capital. YIMBY activism reflects a complex hybrid of a previous century’s axioms of trickle-down filtering theory and contemporary progressive moral-ethical discourses of dynamic, diversifying lived experiences of intersectionality at the scales of individuals, families, communities, nations, and cultures. As intensified urban competition co-evolves with diverse, recombinant axes of Western/non-Western and colonial/decolonial relations of space and time, localized economic rent gaps become transnational, transhistorical moral rent gaps constituted through competing claims for inclusion into the inherent exclusivity of capitalizable property rights. YIMBY activism reveals the evolutionary frontiers of escalating competition legitimating itself on a gentrifying urban planet.