In what version of the war was it worth one trillion dollars of American money to liberate the Iraqis from Baathist tyranny?
I don't know about you, but I'm just not that globally altruistic. I can think of thousands of ways to spend that money in the United States. Or not tax or borrow it in the first place.
Second, you're right: "liberating Iraqis" should never have been the primary goal-- the primary goal should have been and remains US security, which is why we should not have left.
Bush's emphasis on "nation building" was disaster in both Iraq and Afghanistan. Although any mistakes on Bush's part pale in comparison to the deliberate betrayal of the US and its interests by the traitor Obama.
Bush's failure to negotiate (or force) a status of forces agreement with Iraq because he wanted to play nice with the next President was a critical stupidity, which (like many others on his part) shows how he failed to understand that defeating our domestic enemies was as important as defeating the foreign ones.