One way of considering fire safety is known as the layers of protections (or lines of defence); also known as LOPA. This simply means we need a number of protective layers between an initiating event and people exposed to the consequence of such event. A visual way of presenting the layer of protection is the Swiss cheese model of accident causation by James Reason. This model likens protective systems to multiple slices of Swiss cheese, stacked side by side, in which the risk of a threat becoming a reality is mitigated by the differing layers and types of defences which are "layered" behind each other. Therefore in theory, lapses and weaknesses in one defines layer do not allow a risk to materialize, since other defences also exist, to prevent a single point of weakness.

Though the cost of firefighting system is justified, it is just one layer and you can’t expect them to reduce risk to near zero. You need many more layers (according to Swiss cheese model) to achieve very low risk.

Another layer can be preventing the possibility of  fire spread by confining the fire, controlling the amount of combustible material, sources of ignition, if possible replacing something which easily burns with something which doesn’t easily burn (this is known as inherently safer design), having redundant fire detection and early warning system, etc.

When it comes to people’s safety you need to spend as much as necessary to reduce the risk below a tolerable level.  This paper might be of interest to you. https://www.researchgate.net/publication/274677545_The_ALARP_Argument

Article The ALARP Argument

well, I thank you for your help

 We running tests of our firefighting equipment on a daily basis. As we work with prototypes we need to take all possible precautions each time we go to the range. However, we work on watermist systems and everyone kept pointing to us that water mist creates a thermal screen protecting the operator. We kept on ignoring this comment, as we have no death wish and were unwilling to test such a hypothesis on our own bodies. One day we realized it has been some time we no longer use any protective gear. Water mist is a very good safeguard, no dubts about it. What I believe will be happening is that with advent of modern firefighting technologies the fire or heat will be a lesser factor and the protective gear will be more like the one used elsewhere, more like army uses for explosion experts and rescue squads for deep underground search - explosions, structural collapse and smoke will be an issue, but not fire, heat and smoke.     

thanks for your help Niels Jensen

Hi Edison,

In light of Mr Jensen statement, read my answer again, in which I have explained how to answer Mr Jensen's concern.