Jethalal can't utter a single word to his wife who always embarrasses him in their balcony
Jethalal can't utter a single word to his fraud brother in law who always cheats him and makes him incur all his expenses.
In short jethalal can't fight against the injustice done to him,whether big or small.But the same jethalal insults people like iyer and even bhide. It seems he removes all his frustrations on these two because these two can't do anything to him.At home he's alone. Nobody will take his side or support him.But outside, his fire brigade Taarak mehta is there to support him even if jethalal is wrong. That's why he humiliates iyer and bhide.
And as other people have written, he has lots of pride and attitude too.He thinks he's great because he achieved success even though he's less educated. He under estimates the educated people by thinking that they can achieve success easily because of their qualifications.But the poor guy doesn't realize that not all educated and uneducated people are successful in this world. Education and hard work are not the only things in this world to achieve success. There's something called Luck too.