Let's not forget that Iraq's population is 70% Shi'a Arab, that it is the second largest Shi'a nation in the world (after Iran), and its members are very closely tied to the clergy that had taken over Iran in 1979. Saddam went to war against Iran also to prevent a similar revolution from breaking out in Iraq.Iraq has only a very small outlet to the Persian Gulf (she has half of the Shatt-al-arab river). Saddam's goal in invading Iran was to gain control over the entire Shatt-al-arab, which would greatly expedite Iraq's access to the Persian Gulf. But after that long drawn-out war, with immense casualties, the Iran-Iraq war ended as a draw, with both nations pushed back to their original pre-war boundaries.
Then, Saddam decided to invade and annex Kuwait. This would also greatly expand Iraq's access to the Persian Gulf, in addition to gaining Kuwait's oilfields. He didn't foresee how determined the American military response would be to preventing this occupation of Kuwait. It wasn't so much acquisition of additional territory, as access to the Persian Gulf, that Saddam wished to obtain.