...we all agree that the right pronunciation of "nitch" is "neesh", though, or at least I've never heard a serious argument to the contrary. People just genuinely don't know how to pronounce it because they've only seen it written.

One that still gets me personally is "hyperbole"--I know how it's pronounced but when I read it, I still say "hyper-bowl" in my head more often than not. I don't think I've ever made the mistake while reading out loud to someone yet, but it will likely happen some day and when it does I will feel very stupid.