What can cause a near fatal brain hemorrhage at 30 years old?

Most likely: Odds are this was due to the rupture of a congenital berry aneurysm, but other vascular malformations might be a cause. Hypertension can do this, usually in older folks, factor S and C, sickle cell anemia, hereditary coagulopathies, medication reactions, BUT, another growing cause is drug abuse with cocaine, and or methamphetamines.