Portugal has two times the population (10.4 million) and 125 times the space (92,200 square kilometers).
The problem isn't tourism (Airbnb) or retiree immigrants (golden visas) occupying Portugese residential units. The problem is inability to build the needed housing.
I can double an investment of 1€ easily; with 100 Million, it is a bit more difficult.
The problem is probably complex, and my bet is it has to do with incentives regarding tourism. When a desirable place gets an influx of people with a lot more purchase power than the locals, distortions happen. Prices, for instance, might reflect what tourists can pay, pricing out the locals. It is a delicate balance, and I guess it comes with globalization.
The problem in Portugal is the relation between income and housing cost. If the average rent of a 1 bedroom is 1000/month, and the average net income is 1300/month, you have a problem.
And oh boy are they building. Entire new zones that didn't even exist 20 years ago are now full of high rise buildings, public transport, shopping malls, ... But the prices to live there are phenomenal, even to western european standards.
Let's try not ruin a beautiful country like Portugal by turning it into S'pore, aye?
Also, at Singapore population density (I have different numbers from the other commenter), even if the entire EU moved there it would still be 42% untouched (and the rest of the EU would be empty).
by any measure (for example wealth, health, social security, safety, housing, jobs) Singapore is outranking most of Europe, including Portugal.
I lived there for a while, and I could go the rest of my life without ever even thinking of stepping foot into that depressing hole of a country again. These cute stats people like to throw around are nice and all in theory, but actually living there is a whole other story.
Maybe things have changed in the last 7 years since I last lived there, but I very much doubt it.