Iron Man, also known as Tony Stark, ultimately killed himself by using the Infinity Stones to defeat Thanos and his army.
While the direct cause of death was the overwhelming energy of the Infinity Stones overloading his body, his sacrifice was a conscious decision to save the universe. Here's a breakdown:
- The Threat: Thanos, wielding the Infinity Gauntlet, posed an existential threat to the universe.
- Iron Man's Choice: Recognizing the only way to definitively stop Thanos was to use the Infinity Stones himself, Iron Man took possession of them.
- The Snap: By snapping his fingers while wielding the Infinity Stones, Iron Man channeled their immense power to disintegrate Thanos and his forces.
- The Sacrifice: The energy output from the stones was too much for his human body to withstand, resulting in fatal injuries. His body simply couldn't handle the power, and he died shortly after the snap.
Therefore, although he defeated Thanos, the act of using the Infinity Stones was directly responsible for Iron Man's death, making it a self-sacrificial act.
