That's the most horrific point of view I've come across in a long time, and I'm completely serious.
No. No. No. Very, very few, extremely disturbed, people would kill or hurt children if given the option without consequences. Even people who "don't like" kids don't want them harm, they just don't want to be around them. If I could do it without consequences, yes, I would massacre a number of criminals. I wouldn't massacre random adults. And I certainly wouldn't harm children, much less massacre them. The fact that you think that "a lot" of people would do it is nothing short of terrifying.
And don't give me that "but you've never been in that situation so how could you knooooow" BS. I've done a lot of crap in my life, not all of it legal or moral, and I can tell you right now that I know I wouldn't hurt a kid any more than I would drop a bomb on a city if given the opportunity. If I can't know that much about myself, then I have no identity, period.