Well I was thinking of agriculture subsidies, which are substantial in both the US and the EU. The US also puts significant subsidies into the Oil&Gas and Aerospace industries.

Right. When the 2010 Haiti earthquake hit, it wasn't a natural disaster that killed. It was an infrastructure disaster that killed. For a country that went from self-sufficiency in food to having its domestic agriculture wiped out from dumping from subsidized US agricultural products.

Then there are the more overt attacks like on Alstom, Toshiba etc.

Agriculture isn't the best example. Agriculture provides for people's livehood. It's the actual industry that national security depends upon. Which is why so many countries subsidize agriculture, it's not a economical decision at all in any regard.

Technology isn't the best example. Technology provides for people's livelihood. It's the actual industry that national security depends upon. Which is why so many countries subsidize technology. It's not an economical decision at all in any regard.

You literally die without food in at max 21 days. Suppose food supply chain got cut because of war or pandemic, you have to be able to supply food locally.

This is not a pure economical issue because it's not about efficiency, it's about have some redundancy so when things get hard, one won't just be starved to death. Afterall, it takes time for the market to adjust itself and without food, there won't be time.

Without control over your technology, you will literally die immediately of an invasion. Besides, it's easier to import food than nuclear bombs.

If we are talking about End of the World level conflict, then yeah no preparation would mean anything, but that's not the case for most of the conflicts, if any since WWII, aren't they?

And TBH, following that reasoning, that there is nuclear bomb, ground force should be cut to save cost and tax money too.

Yes, if you are a country that only wants to protect their homeland, cutting your ground forces as a result of nuclear bombs and ICBMs is perfectly rational.

Say that you are a citizen of a country endlessly threatened by invasion from a foreign power. Is it more important for you that your country has the nuclear bomb, which means your likelihood of being turned into glass falls from 50% to 0.1%, or that your country has greater control of agricultural production, meaning that in case of disaster you won't have to pay fortunes for imported food and cut your consumption? I'd say in this case the nuclear bomb is more important.

Also, we didn't see End of the World level nuclear destruction of any country because all the great world power developed the Nuke. The US Army very seriously considered using nukes in the Korean War as well as had plans for the invasion of the USSR (See : Operation Unthinkable and Operation Dropshot). The only reason these plans weren't carried out is because the USSR and China sacrificed very heavily in order to develop their technology and achieve technological parity with the West.

Tell that to the Lebanese. After the Beirut explosion took out the nation's largest grain depot (half of it got blasted to shreds by the explosion, the other half was contaminated) and the entire infrastructure of their dominant port, they're squarely fucked.

If a country loses access to state of the art tech, they might as well become a third world country within 5-10 years.

Agricultural subsidies are the clearest form of theft from consumers there is. There is zero chance of monopolies in an unrestrained agricultural, oil, or gas markets.

Your better example is Aerospace, but there is no proven reason we need those colossal companies, and a big part of the merger drive that created them us to monopolize access to government contracts. ULA is a perfect example of that.

I think what you miss here is that in addition to efficiency, resilience is important in agricultural (and arguably other industries). Depending on foreign supply is all well and good until there's a shortage. Then you're screwed.

Arguably China have just found this with semiconductors. It was all well and good depending on TSMC, until the US blocked their supply.