We should go the asian route of increasing density and size. It's not like Barcelona is fully developed border to border.
Giving these 10k flats to locals isn't going to put a dent in the housing economy.
This is uncharitable. What everybody wants is for the place they call home, either by inheritance or hard work, to not be harmed by overdevelopment. People will have varyingly (un)reasonable opinions on what "over" means, but even a place with zero development has new residents - people do not live in one place forever, nor do they live forever.