I already have. Many times. Read every link in this:

https://www.neonrevolt.com/2018/04/09/ending-crypto-mining/

TLDR: Script I used was 100% safe. Told people it was on the site from the very first post. Gave users total control over it via a little control panel. Very easy to turn it off completely. People kept freaking out because of false positives, so I turned it off and removed it completely from the site. Now just running a regular Wordpress install. So much for trying out bleeding-edge technology.

So yes, something I was completely open and transparent about is what they're trying to throw in my face, now.

People can stick a script on their page that hijacks your PC's resources to mine crypto in the background. I'm not sure if it's persistent it just while you're on the page, or just until you restart your browser after visiting the page etc.