Rav Levi Brackman has a piece in Ynet asking the question: why is mocking Chareidim acceptable while the reverse, mocking the non-religious, is not?
I'm going to avoid the easy, insulting answers here and try to look at this problem from a serious perspective.
The first reason for the hatred and mocking is the insecurity many non-religious Jews feel when confronted with their observant brethren. Remember that we live in a society that tells us that a religion provides its followers with an anachronistic, restrictive lifestyle that is totally out of sync with the norms of the modern world. Therefore, the sight of a religious Jew who also holds down a normal job, has a variety of hobbies, and is as educated if not more so than his average secular counterpart is a big cause for insecurity. The unstated worry is: if I refuse to be religious because I want to be integrated into the modern world, and this religious Jew opposite me is living proof that one can be frum and part of that world, then where is my justification for my lifestyle?
The second reason comes from the formerly frum, or as I saw them called years ago in an Israeli publication: Baal Sheilahs. Like Baal Teshuvahs, Baal Sheilahs general harbour a certain amount of animosity towards their previous lifestyle. In an unconscious need to justify their current choices, both groups devote a certain amount of disdan and hatred for what they used to be. For BT's, this manifests as condescension for the non-religious and dismissal of their views as much as possible. For BS's (no implication implied) it comes out as a constant mocking of those "stupid, nit picking rules" that seem to dominate Orthodox life. Imagine how easy it is for a formerly frum person to reach out to those who have negative feelings about their observant brethren and to justify those feelings with a selective, negative interpretation of Jewish law and habit.
The third reason is a result of Chareidi Jewry itself. This is not a group with the greatest public relations effort, as is well known. Even their finest journalists cannot avoid supporting what has become the most well-known negative slogan of the community: We're the only genuinely religious Jews out there. Accept no substitutes. It also doesn't help that when this ideal is challenged, the response usual is: Tsk, you just don't understand because you're not frum like us.
Having said all this, Rav Brackman raises an important point in his article:
Let’s put the shoe on the other foot for a moment. What if the same type of story would have been told by a recent Baal Teshuva (returnee to observant Judaism) mocking non-observant Jews? I can just hear the outrage. “How could you be so judgmental?” people would ask. Or worse still, people would rightly accuse the storyteller of religious snobbery and of a reprehensible and insensitive type of condescension and arrogance.
He is quite correct in his assertion. Accuse an Orthodox Jew of being racist, sexist or primitive and you get applause all around. Accuse a non-religious Jew of being immoral or uneducated and you get cries of "intolerant". To a large extent, Chareidi Jews are the Jews of the Jewish world in how they get treated by the rest of us.
And that's something worth thinking about.