I have no real problems with your definition of the state and I read that you - which I really didn't need to read - are aware that the state comprises individuals and that collectives can't act. The problem is that despite your definition and your qualifications you continually talk about the state as a single entity.
Why would the state fear it's own power? I was being facetious in talking about the state, I'm going to stop using that word because I think your keenness on it is half of my problem. I live in Australia, most of my government is a sprawling bureaucracy charged with overseeing mundane things like providing services, overseeing projects, planning, overseeing the regulation of various sectors, dealing with legal problems and so on. Unelected officials who aren't plotting the subjugation of other components of the government. I am sceptical that they even have a clue what's going on in any department besides their own.
Across the ladder, people are primarily concerned with keeping their jobs, doing their jobs and maybe even getting a promotion. Corruption isn't even a viable option for most of them and where it is - they're being regulated by more government bodies that aren't elected, aren't motivated in any of the ways you're talking about.
In the higher levels of government, we have two different parties, liberal and labour that can fill them. A big scandal here is somebody spending tax dollars on an unnecessary or unnecessarily expensive means of transportation. Do politicians care about advancing their career, avoiding a scandal and being elected or advancing the power of a government body that they know they're only going to be in charge of for a small portion of their career? For what?
Corruption exists but it's people using their position to make themselves rich - there's really very little incentive to attempt to empower the part of the government they're working for. They won't be there forever, it's a huge risk, there's no unilateral support and there's likely no support from higher levels of their party - if they even belong to the one that's in power - or one at all.
A totalitarian government is the worst possible thing for pretty much everyone except the ruling elite.
It's not that we should take for granted the checks and balances - also I think Australian democracy is wildly better than many other democracies around the world. So in some countries, the risk is extreme.
I think the concern with totalitarianism is not a gradual and collective descent into power-hungry behaviour by the government. It's power-hungry individuals in the government or often outside of it, who are hellbent on having absolute power. Most democracies that fail have rampant corruption, limited control over the military and haven't been a democracy for long and likely never operated as a true democracy.