It's fairly simple to identify very smart people, but it takes some time. You ask them what their goals and predictions are, and then watch for a while.
I've noticed the smarter a person is, the fewer qualms they have about sharing exactly what they're aiming to do.
This approach is also a simple way to identify stupid people, but for stupid people there are much quicker methods. And stupid people tend to be cagey, because they have fewer tools for identifying when somebody is trying to take advantage of them, and because they've got experience being taken advantage of.
I disagree with some of your observations.
Being taken advantage of is not only a function of intelligence. It's also a function of emotional health. Sure, if the person is incapable of understanding they are being taken advantage of, they will be. But one can be perfectly capable of understanding that, see it happen in real time, and let it happen anyway. That has been the case with me for a long time. I could see, but I could not stop it, because I have been emotionally conditioned to allow it. Took a long time to fix.
There is also a risk of confusing a smart person with a person who speaks well. We have a built-in heuristic, that language signals intelligence. To a large extent it does, of course, but it can be deceptive. I've grown very weary of well-spoken people, who seem to want me to think they are also very smart.
Lastly, higher intelligence does not mean the person is a better human being. I find that there is an obsession with intelligence in the West. "Stupid" people can be really lovely and better companions than smart ones. There is something to be said about kindness and honesty.
> I've noticed the smarter a person is, the fewer qualms they have about sharing exactly what they're aiming to do.
I used to be like that. Openly speaking about what I aim to do and how. I ended up moderating that quality a fair bit after noticing some people began copying my ideas or outright stealing them. I was to slow to execute.