At the very least, consumer connections explicitly disallow "Commercial Use". That means that you can't use them to run a business. You can't use them to turn a profit. You can't use them to generate revenue. That means no running servers, and that means no "reselling 2% of your bandwidth" for a few pennies because some Euro-Trash-Stranger wants to borrow it!
And that's really bad! Far more than reselling, you should very much be able to run a website from home!
No, it’s fair, and probably federally regulated.
You wanna run a business? Then get a business license, pay your business taxes, and sign up for a business Internet connection. That’s what they’re made for. Then run your servers to your heart’s content.