Is that a pre-condition to know about countries, leaderships and general public?

I have not lived in the US, and I know a lot about the US national character.

> I have not lived in the US, and I know a lot about the US national character

That is not a good justification. The US is well reported enough in news and media and movie to have a good awareness of the culture within. You also understand their language.

However, the Arab world is not reported well enough apart from biased sources that seek to defame and discredit them. And neither would you understand their language. So no your awareness of their culture and country and leadership is so far fallen yet you think it is sufficient that it becomes dangerous.

There is no such thing as Islamic population unless you are an Islamophobe who have sought to “other” this part of the world

Yes, I would say that making sweeping statements about a populace does require actual first-hand experience with said populace.