Why does pony collapse after the rumble?

Ponyboy collapses after the rumble due to the intense emotional and physical strain he experiences during the fight. The adrenaline from the confrontation, combined with the trauma of witnessing violence and the loss of his friend Johnny shortly after, overwhelms him. His collapse symbolizes not just physical exhaustion but also the psychological toll that the ongoing gang conflicts have on him and the other characters in "The Outsiders." This moment highlights the futility and consequences of their violent lifestyle.