Power
You have the power to keep people from drowning. That's always a good thing.
Drowning is the second biggest cause of deaths in children and the fifth most common cause of death of humans overall (source).
By teaching kids how to swim, you could actually be saving their lives.
You'll also really help them with their social status. Nobody wants to be chummy with a nine-year-old who goes to a pool party in a life vest or water wings.