Quantifying the balance between continental crust production and destruction at convergent margins is a challenge for geoscientists. Here we address this problem by integrating geochemical and volumetric data of arc and forearc lithologies along the western Mexican subduction zone. Our results show that the volume of subducted continental crust has been effectively counterbalanced by contemporaneous magmatism, with no net crustal growth, at least over the past one million years. Nonetheless, we estimate that at least half of the magma mass of the volumetrically dominant andesitic volcanoes must come from reworking of subducted lithologies in the form of altered ocean crust, sediments, and, most importantly, cannibalized forearc lithologies, incorporated into the mantle wedge as buoyant subduction mélanges. These findings indicate that continents are more resilient than previously thought, and call for a reevaluation of crustal growth models by way of a more careful assessment of the role of subduction erosion in global convergent margins.