The problem is not politicians and politically connected assholes. You had a liberalization of the renting market done by the previous right-wing government, coupled with the appearance of Airbnb and low interest rates for a decade. This led to a situation where it was cheap (low interest rates) to invest in real estate, place your new apartment on AirBnb and easily recover the investment. Old landlords caught up to this and many preferred to evict tenants or increase the value asked to close to what they would get if they rented the apartment via Airbnb. And there was still the many years of golden visas for foreign investors, also implemented by the previous right-wing government. The left-wing government never did anything to change this, because all this real estate investment brought GDP growth to Portugal and when they proposed some semi-serious changes you had everyone benefiting from this status quo screeching that Portugal was becoming Venezuela.
But it’s now got to a point where the prices are unsustainable to almost everyone and as you said a lot of people are excluded from being able to buy a house. And the situation won’t improve in the next couple of years because interest rates probably will take a while to go down. As for the brain drain, that’s an old historical problem. Heck, I had to emigrate last year and I am almost 40. The lack of stable work contracts, the non-existent salary growth from both the public and private sector already made thinking about settling down and having kids hard. These housing prices are just the final blow to the situation.