It's not quite that easy, you can cross the border in the EU, but you can only stay in another country for three months unless you get a job or study. And it could be argued that the EU is a de facto country.
can you even post without telling complete bullcrab? within the EU (schengen treaty) everyone can live and work where he wants.
What is wrong with you? Yes you can stay if you work or study or have a partner there that provides for you, and some additional rules in different countries otherwise you have to leave after three months.
https://travel.stackexchange.com/questions/39201/length-of-stay-as-tourist-in-another-european-country-as-schengen-eu-eea-citize