You rent out the older properties, e.g. one house I rented I got 150% of purchase price as income over 10 years.
It does take time and you have to begin early, the luckiest people have richer parents to get them started.
The tax rules mean you buy a house, live in it, then buy next and rent the previous out. Repeat and when you stop working then see if you need to sell any houses. There’s plenty who own whole streets renting out.
Democracy being what it is means landlords fund parties who don’t do anything, and of course local elections don’t like lots of new house build, so prices go up to profit the local landlords.
And so the world is explained.