I pronounced hyperbole as it is spelled "hyper bowl" for decades and nobody corrected me! It wasn't until I finally saw someone say it in a TV show that I realized the error of my ways. Now I stumble over the word every time I try to say it because I have decades of habit to overcome. Sometimes when I think I might need to say it, I start mouthing it ahead of time so that I get it right on the first try. There are at least a dozen other words like this for me, and I'm sure dozens more that I'm not even aware of.

Edit: for those of you who have never heard it pronounced, hyperbole is pronounced "high-per-buh-lee".