Young Portuguese have been emigrating for the last 50 years. The country is full of second residences, bought by people who took advantage of cheap real estate until recently.
Blaming today's inflation and cost of living on a few digital nomads or crypto people doesn't make much sense.
What also chocked me when visiting Lisbon or Porto is the number of old abandoned buildings in what I would consider nice areas. I have always wondered what was the reason for that...
Building a system & owning it is indeed an investment but often you have much more chance to stick to it long term.
Apps often come & go, transitioning from one to another can be very expensive.
Also if you want to be in control of the security & privacy DIY is the way to go.
It is an ubiquitous legacy, a critical infrastructure of our societies and a spaghetti that cost everybody a lot.
In the end it is controlled by the biggest corporations and various interests. Very hard to disrupt and replace.