I love it when people start trying to assess root causes of project failure and they include unrealistic expectations of delivery timeline and unrealistic budget expectations. Certainly those can cause failure for the standpoint that the timeline and budget expectations weren't met. But whose fault is that anyway? That's like saying "I was late because I locked my keys in the car." Was the problem that your keys were inside the car and it was locked or is it that you caused that to happen? Who is to blame? You are. You're the one stupid enough to lock your keys in the car...