Think about your use of the word serious. Wars are fought until one side decides to stop fighting. Laws are made because people are emotional creatures. I'm not going to get long-winded, but there are plenty of examples of small losses of lives leading to major policy changes, loss of freedom, change of ruling party, decisions to either engage or disengage large military forces etc. Terrorism is an emotional warfare, not one in which you count up the damage on a balance sheet.

The outcomes I mention are extremely serious. Outcomes that are easily existentially important to the state.