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.
If this thread continues for a few more levels, I think you’ll end up justifying hiring your own private police force.
Ownership requires that a state exists to enforce your rights. There are tradeoffs with this arrangement, one of which is that the state gets to set boundaries/limits on how you can use the thing you own. Ideally, acting with the best interests of the population. This sometimes includes ensuring areas are off limits to transient inhabitants so that a society can develop.