I have no insights into internals of Nvidia, but it really doesn’t make sense to me how there is literally no alternatives that are even close to its maturity. I remember in the early days OpenMP and PPL being contenders early on, but I never heard about them after and only CUDA kept going. I was working on a graduate project in 2009 and I remember us looking into OpenMP and CUDA and going with CUDA because we found it easier to use. But also along with CUDA, only Nvidia pushed the whole GPGPU idea and AMD (and Microsoft to some extent) only paid lip service to the concept without any actual commitment like Nvidia did for a long time.