There are ways to dramatically increase or decrease your odds. There are no hard guarantees but statistically it's extremely clear that your lifestyle is a huge differentiator. Obesity and diabetes are easy to avoid for the vast majority of people and will absolutely fuck you up. Even cancers are like 70%+ lifestyle/environmental related.
Just like you have people who survive car crashes in 1980s cars while not wearing a seatbelt and people who die in a 2023 car with 12 airbags while wearing a seat belt. Your conclusion shouldn't be that seatbelts don't do much
My gf's dad was on the way down, 65, getting fat, low mobility, out of breath all the time, &c. we motivated him, he lost 35kg+ in a year, no more shortness of breath, much better mobility, all health metrics improved, it doesn't mean he'll live longer, but he'll for sure live better