why do people do this

[kvn4]

went down to pond for a little freshwater fishing and off to my right i hear splashing in water and lots of squeaking near shore. ok baby ducks washing or playing .this goes on for five minutes straight so i go sneak over to see what the comotions about. well theres a duckling struggling at some weeds so i go through bushes and see its struggling and squeaking like mad in disstress.only way to get to it is into the water.well im fully dressed and without thinking here i go into the water and find hes tangled in discarded fishing line around his leg.after cutting the line and setting it off to be with his brothers and sisters all seemed good. well didnt catch any fish but felt good the rest of my time fishing.why cant people just take their line with them when they leave.them AHOLIES.