Insurers are businesses. They base their price on the likelihood of having to pay out and have huge amounts of data to support this (although I don't think they call it "bollocks").
If they charged me £100 for a group 3 car and they charge a 17yo £2000, it's because their data says the 17yo is...
The sad truth is that a 17 year old bloke is something like 90% likely to have an accident in his first year of motoring.
(me, 46, group 17 Saab, 200BHP, around £1/HP - it gets easier)