I've read all of the Culture novels and do enjoy them. However, I can recognize it as a single-person utopia, which IMO makes it inherently unrealistic. I mean

I've read all of the Culture novels and do enjoy them. However, I can recognize it as a single-person utopia, which IMO makes it inherently unrealistic. I mean that it's a utopia which exists entirely in the mind of one man. That means it has never had to face the issues of dealing with real people and real problems. Assumptions and presumptions that person has about how society works and why people do things are encoded into it. Many of these types of assumptions have been found wanting when they go up against real people. It's even more of an issue with sci-fi, where you can make up any technology you want, and have it work any way you want. For example, in the real world, drugs are a serious problem for many people. The libertarian assumption is that all of the problems flow from prohibition. I'm willing to believe that many of the problems do, but it's quite clear that not all of them do. See the prescription opioid epidemic. In many of the cases, there are no issues with the quality of the supply or the cost of the drugs, but nevertheless, the users frequently overdose themselves or abandon everything and everyone in their life in the pursuit of more drugs. I'm quite doubtful that you could give everyone in the world "drug glands" that give them a hit of as much of any drug as they want anytime they want and not have a large chunk of the population die or become catatonic from opioid overuse, or go psychotic as tends to happen with overuse of stimulants like meth or cocaine, or something else. And of course we have the Minds. Of course everything is nice and easy if you make up the fact that the Minds are perfect benevolent dictators who would never harm a human and always do everything legitimately for the greater good. Humans have never been able to do that, but hey, we made up some super-intelligent AIs that do, because I said so. We've never built a real super-intelligent AI, so we don't know how it would be. Maybe it actually would be a perfect benevolent dictator. Or maybe not. Maybe it'll be just like every human dictator we've ever had, happy to squash anyone who questions its rule. Maybe it'll just wipe us all out for being inconvenient and messy. Maybe it'll go off and do whatever it finds interesting somewhere else and ignore us. Who can say? Bottom line is that it's very easy to make a fake utopia of any ideology at all, as long as it's all in one person's head. A Nazi could just as easily write their own fake utopia where society did everything their way and it all just magically worked perfectly because of course they're right about everything in their own minds. What happened to all the Jews, you ask? Why they just don't exist in our imaginary perfect society! Don't you dare ask any inconvenient questions, can't you see we're building a utopia here!