We wouldn't get anywhere if everyone had to worry about every issue. Do you know about the concept called "clean code"? The idea is that our mental capacity is limited so we should try to reduce the amount of things you need to think about to solve a problem. High level interfaces like JavaScript might mislead people but they are still preferable to forcing everyone to bother with the gritty details of machine instructions.

Similarly when we teach things we start with simple concepts and hide the ugly truths. The simplified versions might be wrong, but they are easier to learn and true enough to be useful. There have been many attempts to stop teaching those half truths and just go to the meaty concepts directly, but all of them have proven to be worse than just teaching half truths first. Thus it seems like people are good at handling being misled and later update their understanding to fit new data.

Ok, here's a "Peter Thiel" secret: The display of confidence today is simply a tool that can be used to motivate, rally, and comfort your followers, for good or bad, in a more visceral and emotional way than intellectual argument alone. I believe that most very successful people who display confidence know this, and can correctly interpret other people's displays of confidence as a deliberate use of this tool.

This is not an evil thing per se, because this is simply how human motivation works -- if a leader is intellectually sound but always externalizing caveats and risks, verbally or non-verbally, he will be less effective than a leader who is equally intellectually sound but uses all the motivational tools at his disposal.

Yes leaders who manipulate and say half truth are more successful. That does not make them more ethical - they are as unethical as I would be if I lied (for example about worked hours on timesheet or about status of the project).

Your comment doesn't address what I said. I did not claim that being non-humble was "evil", and effectiveness is orthogonal.