Much evidence suggests that the wealthiest individuals contribute disproportionally to climate change. Here we study the implications of a continued growth in the number of millionaires for emissions, and its impact on the depletion of the remaining carbon budget to limit global warming to 1.5 °C (about 400 Gt CO2). To this end, we present a model that extrapolates observed growth in millionaire numbers (1990–2020) and associated changes in emissions to 2050. Our findings suggest that the share of US$2020-millionaires in the world population will grow from 0.7% today to 3.3% in 2050, and cause accumulated emissions of 286 Gt CO2. This is equivalent to 72% of the remaining carbon budget, and significantly reduces the chance of stabilizing climate change at 1.5 °C. Continued growth in emissions at the top makes a low-carbon transition less likely, as the acceleration of energy consumption by the wealthiest is likely beyond the system's capacity to decarbonize. To this end, we question whether policy designs such as progressive taxes targeting the high emitters will be sufficient.