For the wealthy this might seem acceptable, but the thing everyone forgets is that the fry cooks and the middle class are not going to go without a fight.
And the first ones up against the wall are the wealthy. No amount of private security, guard towers, and barbed wire fences can stop millions of desperate, hungry people with nothing left to lose.
Unless the poor find a way to efficiently organize themselves, I think private security can easily stop them. In such a dystopian future, a well funded, well equipped, well trained private security force of a 100 can take out a million opponents. When you're in your fortified complex with a mass of people outside demanding justice, you call in an artillery attack or an airstrike.
Tell that to the copiously armed forces of Egypt. Or Libya.
One doesn't need smart bombs or even automatic weapons to revolt, and in a society where the private security patrolling your gates and walls are cousins and brothers to the desperate, repressed poor, you will also have trouble getting them to pull the trigger. This has been a major factor in the Arab Spring.
The rich simply do not live in the vacuum that many of them seem to think they live in.
The armed forces of Egypt declined to put down the revolt, which they very easily could have. The revolt in Libya would have failed if not for outside help from the West. And these are two countries with militaries that have pretty much never won a war against other countries. Libya even lost to Chadians with machine guns mounted to Toyota trucks not so long ago.
If you look at successful revolts in history, usually either the deposed leaders were soft-hearted and let things get out of control (French revolution, Russian revolution), there were powerful factions favoring the revolt (American revolution), or there was outside help (American revolution again, various resistance movements in WWII). I can't think of any revolts that succeeded against sufficiently ruthless rulers without foreign intervention.
Look into the history of the Boer War, the Jacquerie, the US Civil War, or the Roman treatment of excessively rebellious tribes (the Bar Kokhba revolt would be a good place to start).
Getting people to pull the trigger might be a problem in some homogenous country like Finland, but here in the US, the teabaggers hate the occupiers and vice versa, and it would not be hard to get them to pull the trigger on each other. Even if it was, it would be easy to bring in foreign mercenaries who don't particularly care about either group. And if that was too hard to manage, by hypothesis we're talking about a world in which robots are capable of doing so much work that most people can't find jobs. Presumably these robots would make passable soldiers/security guards.
None of this means that the rich and powerful would necessarily have the inclination to brutally put down a revolt. The certainly don't now. I hope they never do. But they could if they wanted to.
And the first ones up against the wall are the wealthy. No amount of private security, guard towers, and barbed wire fences can stop millions of desperate, hungry people with nothing left to lose.