Before revision:  Moreover, this effect is much stronger for "luckiest draw" recipients or those who receive the largest share from a red packet, suggesting a group norm according to which the luckiest draw recipients should send the first subsequent red packets.
After revision:  Decomposing this effect, we find that it is mainly driven by the extensive margin -- more recipients are triggered to send red packets. Moreover, we find that this effect is much stronger for "luckiest draw" recipients or those who receive the largest share from a red packet, suggesting a group norm according to which the luckiest draw recipients should send the first subsequent red packets.