> That said, there it is not difficult to overstay the standard 90-day EU visa and simply pay the fine when leaving / on the next entry.
Don't do this. Customs officials really don't like it when you show a flagrant disregard for their laws. Also, you can create permanent problems for yourself if you ever decided to return.
I certainly did not imagine doing this on my own, nor have I tested the limits first-hand. The self-sufficiency permit isn't that difficult to obtain for a committed nomad, as I see it.
But the chatter in the Greek expat forums specifically describe the purely financial nature of the Schengen zone penalty: pay-to-play. The punishment comes in the form of the fine amount, which in a range is left to the discretion of the customs agent. Evidence of "flagrant disregard" or an otherwise spoiled attitude might get the maximum fine, whereas an honest mistake (or an engaging attitude) might cost only a few hundred euros.
Don't do this. Customs officials really don't like it when you show a flagrant disregard for their laws. Also, you can create permanent problems for yourself if you ever decided to return.