Can you die from obstructive sleep apnea?

Indirectly: Untreated sleep apnea causes drops in oxygen levels during sleep, this causes a release of catecholamines which are of "stress hormones". Over time this can increase the risk of high blood pressure, diabetes, heart disease, and pulmonary hypertension. Overtime these can lead to death. In addition the sleep deprivation leads to increase car accidents, which can be fatal. Treatment helps avoid this.

Yes: Severe osa can kill. If encounter illness, require more gas exchange to maintain oxygen and acid-base balance. If unable to meet this demand, carbon dioxide builds up and, at high levels, is an anesthetic. If not intervened, will die rapidly. I intubate people literally on death's door from osa daily. Same can happen with even low doses of narcotics with osa.

Yes: It increases you risk of heart attacks, stroke, and car accidents.