To be fair, "Haupt" in german can mean "Kopf" (head in english) so weishaupt and weiskopf (pronounced badly) can mean the same thing...
That could be because they don't know (or don't care) that it's a german name. I get why english speakers who don't know that would pronounce the first part "wiss" instead of "wise" because they don't know that "ei" is always pronounced like "eye", and the second part might be "hopt", not "bop" because of the similarity to "caught" or something.
Ouch, ouch, alright, alright, I'll show myself out...
I would be fine with "Weis" being "wees" or something as English speakers get that wrong commonly, the "haupt" part I expect to sound like "hawpt" as other 'au' spelt words are pronounced this way. I fully expect the words in the name to be pronounced correctly. To have extra letters added in and some of the original removed makes no sense. It's like when people intentionally do it to be "funny" which doesn't work here.
I don't mind saying it different here as people are going to think I'm some prick if I say "veiss howpt" So I will say "weiss hawpt" instead. Though I find myself going back and forth on the second half of "haw or ow." It just bugs me when someone says it waaaaay off.