> During the last two decades and a half, important changes occurred in the realm of rice production and profitability. First, the cost of producing rice is several times higher than potato but the rate of profit is more than double for potato. Second, the yield of wheat, jute and potato has increased over time but the yield of rice has almost doubled from 2.16 t/ha in 1988 to 3.7 t/ha in 2000 and about 4.6 t/ha in 2014.
More than a factor of almost four increase in the yield of a staple crop that has been grown in that region for a thousand years is a technological miracle.
>The country is notable for its soil fertility land, including the Ganges Delta, Sylhet Division and the Chittagong Hill Tracts. Agriculture is the largest sector of the economy, making up 18.6 percent of Bangladesh's GDP in November 2010 and employing about 45 percent of the workforce. The agricultural sector impacts employment generation, poverty alleviation, human resources development and food security. More Bangladeshis earn their living from agriculture than from any other sector. The country is among the top producers of rice (fourth), potatoes (seventh), tropical fruits (sixth), jute (second), and farmed fish (fifth).
To get a perspective: look at the map of egypt and map of their population density. Half the country is pretty much in Nile Delta and most of the rest is along Nile.
Closer to home, South Florida will eventually have similar problems. The whole region sits on permeable limestone so dikes are pointless.
That leaves emigration or mortality increases, barring further food miracles.
Most people in those countries do not consume large amount of meat, massively reducing their need for large amount of agricultural land.
Soil fertility is just part of the equation, does not explain Egypt, Pakistan and a multitude of other countries.
As you said, US has only a 3rd of the population. This is probably the reason they are the largest exporters of food in the world.
You clearly haven’t been to Pakistan anytime recently