I remember working for a small local ISP in the late 90s. We didn’t offer unlimited accounts and charged people overages for any hours over the amount they selected with their account. As an employee I didn’t have these restrictions and even put in a second line in my house so I could use the one modem 24/7 and use the 2nd line to double my bandwidth (to a whopping 67Kbps) overnight. I ended up using more time in a month than there was actual hours. One month as a joke the billing manager sent me the bill that I would have received if I was a normal customer and it was thousands of dollars. I want to say I got the hint and started using less time and resources, but honestly thinking back on it, I doubt that was the case.