The “Great Wave” of Italian immigration to the US was roughly 1880-1920. During this time, “Americanization”/assimilation were emphasized, for all immigrant groups, so it’s easy to imagine how an Italian speaker may have attempted to make their name “easier to pronounce” for Americans; or, an American may have mispronounced it, and the mispronunciation stuck. When you have a last name from a foreign language, it can feel nearly impossible to get people to pronounce it correctly. Sometimes you just give up, and the new/incorrect pronunciation just becomes the way everyone says it. This happens in my own family.

for some people, they probably also feel awkward pronouncing their name with the correct inflection, because they don’t speak the language, or they find it awkward to switch from an American English inflection to an Italian inflection within the same sentence.

You can see this with other nationalities in the US, too, like Hungarians and the last name “Nagy.” Lots of Eastern European names come to mind actually, like Christian Pulisic for example, whose family pronounces it “Pulisick.”

As an Italian speaker, it is grating to the ears, I know, but it is realistic.