Infill is pretty common in cities where real estate is expensive. I’m not sure what the “tipping point” is but large chunks of the city of Boston are built on what was water. The neighborhood “Back Bay” is named quite literally. NYC likewise has large chunks of prime real estate built on artificial land. Manhattan’s Battery Park was once water. The motivation here does seem to have been economic.
Singapore also is similarly growing out into the sea, though the motivation there is the lack of land in other directions, not merely price.
The Aztec city of Tenochtitlan was similarly built in the middle of a lake on a foundation of floating grass islands called “chinampas.” Here the motivation was martial - the lake served as a moat for their imperial capital.
Venice was built similarly to the Tenochtitlan on mostly a series of man-made islands, though the motivation seems to have been population growth.
The Chinese today are building artificial islands in the South China Sea, the motivation here is martial/legalistic - expand the land territory and power projection to expand their claim to the sea.
Manhattan Cruise Terminal in Hell’s Kitchen was constructed by cutting out parts of midtown Manhattan’s bedrock, in order to make the piers long enough to accommodate modern cruise ships. You can see on the map that those piers cut in noticeably further than any others.
The tradeoff is between urbanization (think Singapore) vs nature vs agriculture. The Netherands doesn't want or isn't ready for building tall yet, for some reason.
>> Population • 9 November 2024 estimate Neutral increase 18,212,400[7] (69th) • 2011 census 16,655,799[8] • Density 520/km2 (1,346.8/sq mi) (33rd)
Compare with Singapore:
>> Density 7,804/km2 (20,212.3/sq mi) (2nd)
Singapore is ~56x smaller than the Netherlands which makes it hardly comparable..
People may disagree with this but IMO Tulare Lake illustrates that it's not just "real estate" because plenty of real estate is basically worthless. In this case it's land with water which can grow things (same in Netherlands), and they made more of it by continuing to suck more water out of the lake than rainfall replenished.
Complaining about real estate prices is like going touristing and complaining that the place has too many tourists.