eg: In a pinch meat animals can be slaughtered and eaten and what they once ate can be fed instead to humans.
It's the insurance of being not far removed from near sufficiency.
Basically, it's a lifestyle and politico-economic choice, not a need.
The answer lies between your initial zero and your over dramatic 3x imaginary ball of dung.
If your government is sensible and transparent I'm sure there are public domain white papers that cover their discussions and recommendations which might make for an interesting read and put an end to this silly posturing.
Where? You are just expressing a political preference and hand-waving to unnamed experts. By all accounts, Europe is overproducing agricultural products and the large part of EU's policies are aimed at limiting this surplus.
The counterpoint here is what gross tonnage per annum does the population of the Netherlands consume .. and in the event of supply chain disruptions, should (say) NATO hiccup, to what degree are they self sufficient?
Farming and urban land uses aren't a straight either|or, they're a complex need both.