Romney lost for the same reason why most Republicans lose. They hire advisors and managers who are just doing a job and don’t actually agree with their boss. As a result they accepted nearly everything phrased in a way to support the Democrat.
Mittens lost because—he was shaken by the debates—Candy tossed him a lie—that Obama said it wasn’t a Video in a talk at the Rose Garden. Mitt—too much of a compromiser—not a leader. He was a weak guy—still is.
Just what Romney believed is hard to say, but I think you're on the right track.
Obama's people really believed in winning the election.
Romney's guys were more interested in advancing their own careers and setting themselves up as screenwriters and such.
Obama spent money earlier and then, in the later phase of the campaign, concentrated on getting the vote out.
Romney's people thought they could sway the masses with late advertising and really muffed the get out to vote campaign.
The Obama team's approach turned out to the right one (which the Romney people should have realized going into the campaign).
The 47% remark and everything it represented was the last straw that really did Romney in.