It was and still remains the right thing to do despite the cost. Iraq is the most democratic country in the Arab world, thanks to that war.
And as we've seen in Syria, there are things worse than the addage of "installing democracy at the point of a gun", a stupid saying 2003, made stupider by the fact that the alternative to it is a Syria-style blender of death.
And without Saddam removed, we would have seen what we're seeing in Syria, in Iraq, which would have been bigger and worse.