Why do I have to be added on the car insurance?

Insurance... please support?
Planning on hiring a car in the 25th to the 29th
"Just how much approximately to get a 17 yr old using a 250 ninja? How about a motorcycle? I do not have my drivers permit however"I'm currently house shopping and my employer mentioned raising my auto insurance coverage to cover the buying price of my household I enter an accident where the damages are more than my  insurance