When I was a kid, I learned a lot of words and abbreviations entirely from reading, not from hearing the adults around me use them. (Or maybe they did, and I was just ignoring them.) So I understood what etc. meant from context, but I always pronounced it ee tee see. I didn't know about the phrase for which it's an abbreviation. Later, I studied Latin in school and felt rather silly about ee tee see. (But by that time I was around 12 or 13, so I could look back indulgently at my naive younger self.)
Two more were Yosemite and Thames. As a kid in South Africa, I was of course hooked on comics, but that meant English and American ones, so they were filled with place names I knew nothing about, so I pronounced them phonetically. I once referred to the river as the Thayms and was quickly and scornfully corrected by someone. I didn't have any occasion to mention the character Yosemite Sam, whose name I pronounced Yo-zmyte Sam. (I loved that character and still think he's kinda cool.) Some time after we moved to the U.S., someone mentioned Yosemite Park in my hearing, and a bright light dawned. "It's Yo-semmity Sam!" I said to myself. "That sounds so much niftier!" Or whatever word I used at that time.
There must be a lot of other examples that I've forgotten, and I bet such errors are common with children who learn a lot of their vocabulary from reading and not from hearing the words spoken by the adults around them. I wonder how often such mispronunciations persist into adulthood.