his motivation was an goopy aggregate of many factors, not just defense contract dollars for cheney and pals. the old guard neocons were terribly worried about america being perceived as too soft internationally and the fate of israel; the fundies were scared of the brownskins and islam; and the nationalist/fascist set was hopped up on general jingoism. the administration is a conflation of all those factors, including that of the industrial-military set, and the umbrella policies of the BA really reflect that rather than the machinations of just the monied elite.
sometimes occam's razor, in its desire to shave away complexity, manages to completely miss the skin condition. apf is right, here; OMG OIL INTERESTS or OMG DEFENSE CONTRACT PAYOLA is a better rallying cry for the disenfranchised than it is an actual explanation for our Iraq presence. Bush is purely a creature of influences, and he found himself in political debt to and surrounded by all the influences listed above, from crooked defense men to fundies to nationalists to the pro-Israel neocon contingent to the Young Republican pre-emptive democracy set.