This is correct, but neglects the compounding effect.

Insurers are also adding some %+ increase on premiums every year, which is taken as a % of their yearly spend, ie 2-3%.

ie (1+inflation)^N*(base_prem+overpay_prem_increase) = new_premium. The compounding of $ returned is pretty big on this.

That being said underwriting risk, under the law and avoiding correlated risks, is tough.