Most car crashes are extremely preventable. Do some people not drive more dangerously because they believe themselves to be safe because of things like seat belts?

You are so right. I never understood the prevalent idea that traffic accidents are somehow random rolls of the dice. Seemingly the vast majority of them are not. Adjust your speed, not too fast, not too slow; stay focused on road, mirrors, and other traffic; keep your distance; don't be drunk; don't fall asleep; know and follow the rules, and you will hugely reduce your risk of harm.

> I never understood the prevalent idea that traffic accidents are somehow random rolls of the dice.

It's pushed by the auto manufacturers and insurance companies to normalize driving and make you pay for more expensive safety features. If people drive irresponsibly enough to wreck their cars, but not enough to kill themselves (modulo the safety level of their car), they buy more cars and spend more money on car insurance.