In big companies, it's rarely the success of the project. Usually it's a combination of keeping your job and growing your career.
Most big companies provide limited upside for success, and the downside risk is higher for the people. Consider:
1. The project is successful. You get a nice little bonus at the end, if anything. Maybe a promotion a year later.
2. The project is a failure and people can point part that you were responsible for. You get nothing, or worse, you're fired.
3. The project is a failure, but people can't point at you as the reponsible party. You keep your job, even get a small raise because you did your part.
Part of this is inevitable in my opinion, but organizations should really ask themselves what behavior they're incentivizing and rewarding, especially in a repeated fashion. If your people swing for the fences and miss -- what happens, and how does that compare to the people who bunt or stay on the bench?