The point is that GPU instances are different. The usecases like ML training or general HPC are sufficiently isolated from the rest of your stuff that you don't

The point is that GPU instances are different. The usecases like ML training or general HPC are sufficiently isolated from the rest of your stuff that you don't really need all the bells and whistles that aws has. If you want to host a niche gpu database like production system, you may get more out of aws's ecosystem, but even then, the cost difference is huge.