I remember a couple of TV programmes explaining the situation, with interviews to not only Spaniards but people from other countries too, who were living in Portugal for a few months and/or buying houses there. There was even an agency with travel plans etc. so they managed everything and holders simply enjoyed their vacations.
I know that there are agencies that help in this process. But I had no idea that Spaniards linked to crypto were coming here. The fine is also usually discreet and therefore ends up being normal.
I also believe that most of these people don't come to more urban areas, like Lisbon. Prefer to stay in Alentejo and Algarve (warmer weather and better beaches).