It's hard to evaluate health risks. A 30% risk of having more than one brain aneurysm... well, that means a 70% risk of not having one, right? On the other hand, only 10% of Americans have diabetes and it's considered an epidemic.

It does mean 70% chance of only having one.

Diabetes is an epidemic because of the number of people who have it, not the percent chance of getting it.

"Cigarette smoking and possibly also age and female sex seem to be risk factors."

So cigarette smoking is definitely a factor but it's inconclusive that age and gender are factors, too.