Preservation of the soul

1. Why did most of the jurists take the verses “And you shall be very careful for your souls/ Only be careful for yourself and keep your soul very safe” out of context? After all, the passages deal with the fear that the Israelites would worship idols, or make images of the deity, after entering the land? Is this merely a reference?
The same is true of the Gemara in Shavuot, which teaches that a person is forbidden to curse himself, since “May you be protected and your soul be protected”?
2. Why did the Sages decree things related to danger? Was it enough to warn the public that such and such a thing was dangerous?
3. Nadav Shnarb writes (Keren Zavit and Ve’tehnan): «In any case, a problem has arisen here that must be considered. The assumption that a person is forbidden to expose himself to danger, or the perception of “and you shall be protected” as a complete law, led the poskim (Rambam in the Laws of Murder, 151 and 152, Shulchan Yod 155) to present a list of things that are forbidden to do out of concern for human life: drinking contaminated water, eating fish with meat, “one should be careful not to put money in one’s mouth”, “one should not stick a knife into an etrog or radish”, drinking water from tunnels at night, etc., etc.
There is a problem here. The Maimonides and the Shula more or less quoted things that were said in the Gemara, based on the scientific knowledge of the Amoraim. In our time, when statistics are widely used to determine the benefits or harms of certain health and dietary habits, there is essentially room for turning everything into halakha. Rabbis who “go with” this trend “ruled” that it is forbidden to give the territories of the Land of Israel to the Arabs, that it is obligatory to give the territories of the Land of Israel to the Arabs, a ban on smoking, on driving above the speed limit, and so on ad infinitum. In principle, it is not impossible that a certain rabbi will decide that the speed limit should be limited to 30 km/h (there is no doubt that this will prevent most traffic accidents), or will propose drastic restrictions on carbon dioxide emissions for fear of global warming, or will prohibit the consumption of fattening foods – the sky is the limit.
If we want to prevent the “explosion” of halakhic law, and the debasement of the rabbinical institution caused by the rabbis becoming the mouthpiece of every health trend and every hysterical fan who disguises his words with scientific platitudes, we must, it seems, adopt some principle of common sense of the kind proposed by Rabbi Nansich (comparison with ordinary risks that people take on themselves, such as sea and desert journeys) and Rabbi Moshe Feinstein (who planted the law “in human reason”).
On the one hand, I understand that the explosion of Halacha must be prevented, but on the other hand, I don’t understand what benefit the Sages gained by regulating it? After all, what’s the point of warning against things that appear dangerous to the public when the truth is the opposite?