He's probably buying it so that he can ski through miles of virgin forest with his Norwegian bodyguards. I hate this weirdo but he's probably not going to do much to the landscape.
That's the whole point, it's not invading. In the nordics, land outside of your immediate yard is for everyone, and there aren't many exceptions to that. You get exclusive access to financial gain from it, that's it.
What about fences? I see that people have the right to roam but how are fenced-off areas dealt with?
Not to fence off people, need good reason like dangerous industry, farming animals and such, even if there's a fence you can still enter the land. Can't even put up a sign saying it's private land without permission.