No, it is just an hypothetical scenario but worries me if since our aqaid(belief) is derived from the quran, any person can just pick up the quran and understand it and interpret and will come to distorted conclusion and will be deviated, and for sure it will affect his belief, how do we protect ourselves from this deviation? Or for example, if there is ijtihad(to have conclusion based on reasoning in fiqh), can also someone derived conclusion based on his reasoning about his belief based on reading the quran?

Islam is a comprehensive religion. The Qur’an gives us the guidelines, but the details, terms and conditions we get from the Sunna (the hadith of Ahlulbayt). So I can’t just pick up the Qur’an and come up with my own understanding. I have to be an expert. I must know Arabic very will to understand the Qur’an. Then I must look at the Tafsir of those verses, and also the hadith of Ahlulbayt (a). That is why we follow scholars because they are experts in this field.