[CoolNard]

That's the reason. The thought that crime will always happen spurs people like Kira on to put an end to it, no matter how impossible it sounds. Just because it seems so far away doesn't mean it cannot be achieved. All the more we shold strive for it. And besides, the word here is "probably". I would do the same thing too, if the world government was corrupted.

Being afraid of committing crimes is better than living in a world of sins and misdeeds. And kanji, the word is "if". It won't happen because he'll be supported by like-minded people who know that the world would be much better off without evil. Why afraid all the time if you dont' do anything bad? See what I mean? It forces people to behave well, which is better than what the world is now. furthermore, even if kira himself couldnt do it, we'll help out

Oh Rikku, so there you are! =P Ok, basically, even if someone other than a criminal gets in his way and hinders his mission, Kira will still put the welfare of the rest of the world above that peson's life, so in this sense, the end does justify the means.