Quoting CoinHive's site:

> [...] There are solutions to run the Cryptonight algorithm on a GPU instead, but the benefit is about 2x, not 10000x like for other algorithms used by Bitcoin or Ethereum. This makes Cryptonight a nice target for JavaScript and the Browser. [...] Our miner uses WebAssembly and runs with about 65% of the performance of a native Miner. [...]

Can you actually use WebGL for this? I mean, don't you need a user-visible graphics context? That's a serious question, I have used WebGL only once in my life and that was years ago.

On the other hand, WebGPU looks exactly like the kind of technology that would make web-based GPU-enabled bitcoin mining realistic.

It doesn't have to be visible. You can use display: none or whatever to hide it.

You could put it off screen.

But if most users have integrated graphics, and even with dedicated graphics cards the improvement is nowhere near an order of magnitude, would it be much better?

That $500 was probably what they made within the hours they tested the code, as they do millions of pageviews an hour. Reddit still thinks they're lucky to cover a handful of servers LOL.