How do you know that?
I used to be one. In two years we went to two false alarms. However, it can be dangerous. I lost a high school friend who ran into a burning building and never came out. That was before air tanks and our training never mentioned the absence of air to breathe in many burning buildings.
I don't have statistics to prove my point but I do have my own experience and that of friends and family members who are/were also firemen. We were a medium size city with about twenty fire stations.