If  I found a wad of money on the ground would you keep it or give it back.  I would return the money because it’s not your money to keep.  You would fell guilty or bad about stealing it sooner or later.  That person might feel mad or unhappy because they worked hard for that money.  They could buy a decent bike or toy.  You probably be convinced to keep the money but don’t report it to the police or someone.  Have respect and return it.