This was inspired by another post about killing a baby/puppy/kitten for a billion. He's mine though:

You get $5k for every terminal child under 5 years old that you kill.

You are being paid cash, the children are all terminal, but you don't know their estimated life span. The parents have signed up for this service knowing that their child will at least pass painlessly and quickly.

There will be no legal recourse, and no revenge seeking from families.

How many kids could you look in the eye and end the life of?

Second, optional part: Would you still do this if it was to be a world-wide known fact of who you are and what you do? Still no legal recourse from any government, and no retaliation from families or any activist groups; but everyone Knows.