Generating Passive Income using a PC?

I have seen quite a few blogs and sites like my own that are pushing this idea of selling your un-used computing power to generate income. Some sound reasonable, $1 +/- per day, while others are astronomically high at $1000 per day or more.

I believe that with the proper safety you could be using your PC to mine crypto, but I also believe your PC would have to be a custom built monster. With the way cryptocurrencies work, unless you are operating a beast of a PC with multiple cards and a crap ton of processing power you just aren't going to be able to compete.

This notion of letting companies use a partitioned part of your pc, while sounding great on the site, makes me think it's more of a very small amount of money per day - which is fine, stacking passive income ideas is a proven method. However, downloading software to use on your PC? No thank you, sounds wayyyy too much like a scam.