This. There's a reason that communist revolutions were fueled by a desire for bread, peace, and land. In the start of the 20th century, you could make a decent living if you owned nothing but the land you lived on.

Nowadays, you really can't.

I wonder what happens if we get robots that can provide a complete living off some plot of land. Like agriculture, energy and whatever you need. So in theory you could live autonomously then.

Somehow I think the owning class will come up with ways to make this illegal or impossible.

Why would robots make a difference? Currently, you can't really live off of a plot of land alone, but you'll be living quite well if you also own a bunch of high tech machinery to farm it efficiently. For a well-off Ferrari-owning farmer, the Ferrari is likely not among the most expensive vehicles he owns, the tractors/combines/whatever cost the big bucks.

That's what the poster above meant by "the primary income sources from open spaces now requires massive amounts of capital to be competitive", and owning these robots would be the massive amount of capital; you'd be able to sustain yourself because (and if) you'd have a lot of very expensive robots, not because you just had some land; and you'd also be able to sustain yourself by just investing the value of these robots.