Oh...I Mean Oy

Why does the Yeshivishe Velt pronounce the "o" sound like it's "oi?" I mean, Chassidim, so they pronounce things different because that's how they believe the vowel is pronouced, they really think (and, you know, are possibly right. Who knows these days?) that a kamatz, which we pronouce as "a" (as is as Yisrael), is pronounced as "u," and that a kubutz is really pronouced as "i" (as in Yisrael), etc etc. If they're going to go like the Chassidim, go all the way. You can't pick and choose.

Or am I missing something here??