You can’t afford to buy a new home if your home burns down so you buy insurance. You can afford to buy a new tyre if it picks up a nail so you self-insure, in other words don’t buy the insurance.
I think Road Hazard was about $7 a tire when I bought my last set. (from Firestone) That seemed reasonable to me, so I got it. That said, I’ve only ever used the Road Hazard coverage once in the last 15 years or so. I’m sure that’s what tire dealers rely on for profitability.
Either way you go, I think $20 is a total ripoff.