Earlier quoted context omitted.
Would definitely have been nice. But if you're thinking about scientific programming, it's not so much effort to use AWS GPUs. I do that, and don't think I would buy an eGPU even if it was CUDA capable.
Isn't AWS expensive in the long term? I want to have a 1080 Ti but I don't even have a desktop to begin with.
Checking out whether the pricing works for you is an easy exercise. A p3 instance costs $3.06 per hour at the time of writing. It runs an Nvidia V100, which costs around $10k. So you've got yourself around 3000 hours of use before it makes sense to buy your own.
If you want something cheaper, you can go with the p2 instances at $0.90 an hour. These cost around $2k, so you're looking at around 2200 hours of use before it might become economical to buy your own.
I don't want to sound like an AWS fanboy, but I do believe it's a good democratising catalyst for deep learning and scientific computing.
EDIT: p2 instances run on K80 GPUs, which I neglected to mention above.