(Throwaway account because I work at Amazon)
Everyone at Amazon is focused on AI right now. Internal and external demand for GPU resources and model access is off the charts. The company's trying to provide enough resources to do research, innovate, and improve business functions, while at the same time keeping AWS customers happy who want us to shut up and take their money so they can run their own GPUs. It's a hard problem to solve that all the hyperscalers share.