Interesting…is it severe? Is it some hereditary condition?

Could be. I'm in the same boat (tons of outside time as a kid, very little screen time, significant myopia by age 6-7).

Both my parents are past -8, maybe -9 or -10? I forget, got some realllly thick glasses.

This is like saying “well I’m 70 years old and perfectly healthy after smoking my whole life”.

We’re talking about probabilities and statistics over large populations. Not every child who plays outside will avoid myopia, like yourself. But looking at the population, the expectation is that children who get more sunlight tend to have a lower incidence of myopia and weaker myopia.