ARM made an architecture and CPU/GPU designs for others. They really had no stake in the chip making game, instead having others - Samsung, Apple, Qualcomm, Hua

ARM made an architecture and CPU/GPU designs for others. They really had no stake in the chip making game, instead having others - Samsung, Apple, Qualcomm, Huawei, Mediatek, Rockchip, etc make the chip (that being a list of competitors for Nvidia). Their business model was in making the ARM ecosystem available for all manufacturers (including Nvidia) in order to sell licenses. This, I think, is the primary reason ARM chips dominate at this moment.