Once the “genie was out of the bottle”, Russia at least was going to develop nukes. One of the more dangerous scenarios is one where only one country has nukes. Then they can hang the threat of a nuke over your head, and there’s basically nothing you can do, but call their bluff.
Eventually, people figured out that nukes can neutralize conventional threats either militarily (if West Germany got over run by Soviet tanks, we could start nuking the tanks), or politically (invade my country and I nuke your cities).
Right no, we basically have them so that we are even in strength to Russia and China. France and UK have them to buy admission to th UN Security Council and meeting on European Security (for a while you “didn’t have a real 20th Century military” if you didn’t have nukes).
India has them as a check on China (from way back). Pakistan has them because India has them.
If Israel has them, it to keep their neighbors out of Tel Aviv. Iraq wanted to pretend to have them to keep Iran out. Iran probably wanted them to buy admission into the “major powers club”, but many just because Saudi Arabia doesn’t have them. Post-2002, Iran knows that having nukes would keep us out.
Trust me, FRiend....they do.
There is a story that during the 1973 war, then-Prime Minister Golda Mier ordered some Israeli air force planes to be armed with nukes and put on stand-by alert. She did this because it was looking grim for Israeli forces and the US hadn't yet committed to help (we eventually did and things turned around). She was ready to activate the "Samson Option" if Israel looked like it was going to be over-run.
Israel has (pretty much) admitted that they DO have nukes, but not as an offensive weapon. They're surrounded by countries that wish them to disappear. They are a very small nation, and they have a history that shows them what happens when someone decides they want to kill them. They have vowed "Never Again"....and they mean it.
Along with that...I don't think any RATIONAL nation wants to be "the one" to use a nuke first. If one is ever used, it'll likely be a rogue terrorist organization OR a country that cannot be described as "rational"...like Iran. Any use of them after that will probably be in retaliation AND with the hope that the retaliation will be enough to deter any escalation.