Many countries get into wars because of miscalculations and ignorance about the other side. After the war is over, presumably at least one side regrets that the war started.
The great worry is that Iran has a record of ignorance about the outside world, and a record of miscalculation that suggests that we have to be worried that in a crisis, they would miscalculate and would think that their threats would cause the other side to back down, when in fact the other side would stand tough and we would get into a war that neither side wants.
That, I would suggest, has happened very often in history, and indeed in many ways it's what happened with the Iran-Iraq war. You might think that after having lost several hundred thousand of their citizens in a bloody eight-year war, the Iranian leaders would be much more cautious. Unfortunately, they're not, and the fact that the nuclear program is in the hands of the Islamic Revolutionary Guard Corps, the exact same group that is also responsible for supporting terrorism, is not encouraging when we think about how they might be willing to gamble that a tough stance will cause the other side to back down.