Yep that's pretty much it... a sort of vicious circle. Crops remove the nutrients from the soil, which we never fully replace with synthetic fertilisers, cause these only provide soil with NPK and in turn our food grows nutrient deficient, which means the quality of our diet declines over time. And we try to fix it by eating more, which has more of an adverse effect on our health actually, but the food market grows, cause farmer get paid by the weight... and our soils become poisoned and depleted of nutrients due to intensive farming practices.