Most people don't make over $1 million dollars in a lifetime. I like to think the value comes from the desire to compensate a family member for a lost loved one. Some manner of putting a dollar value of the pain of the loss.
Also the greatest impact of spent dollars comes from investing in knowledge creation since new knowledge benefits everyone who will exist in the future, and we are extremely close (on the earth time scale) to our species becoming effectively permanent (space faring). So any minor new discovery can have enormous benefits, or at least benefits that are many orders of magnitude greater than stopping any number of different terror attacks.
You also have biological terrorism to worry about. Both natural (new severe viral outbreaks as in 1918 virus) and man made threats, which are not included in any estimates of the toll of disease.
Also the greatest impact of spent dollars comes from investing in knowledge creation since new knowledge benefits everyone who will exist in the future, and we are extremely close (on the earth time scale) to our species becoming effectively permanent (space faring). So any minor new discovery can have enormous benefits, or at least benefits that are many orders of magnitude greater than stopping any number of different terror attacks.
You also have biological terrorism to worry about. Both natural (new severe viral outbreaks as in 1918 virus) and man made threats, which are not included in any estimates of the toll of disease.