And what, have it serve as malware/phishing? Thankfully most people still seem to have morals and not fallen prey to pure capitalism

You are thinking all wrong, I wouldn't want to connect some hardcore wirefraud to myself.

I would have found someone on upwork to write me a firefox fork that contains a crypto miner.

The website would have some small print checkbox, making end users actively consent to mining crypto as payment for using the browser for free.

Pretty good place to download Chrome or IE, depending who bought it.