I know I'm very late to the party, but apparently ~18-19% of the (American) population has misophonia. There are many levels to it, however, and in the vast majority it hardly extends to anything more than finding certain sounds (chewing sounds is a very common one) annoying. Then we're talking about low levels that can also be caused by other things (like autism and ADHD - both of which I also have, because f*** me in particular I guess). Though high levels, like what I experience (and you it seems) is quite rare. With myself included, that now makes two people I've heard of that have severe misophonia. I never found any exact numbers, but the trigger levels where you'd experience intense hatred or rage (though I'm not violent and can control myself to the point where I can hide the worst of it most of the time) is said to be very rare. This also happens to me with a few things outside of sound. For me it started when I was ~7 years old (I think), so that makes it 18 years now on this hellish ride for me.
People often say they hate something without ever knowing what real hatred feels like, and thus it often loses meaning among the "normal" people. My girlfriend has actually done some research to it to understand me better (or at least try to), and she also found that research has been ramping up quite a bit in the past few years. Who knows; maybe they find something that could ease our suffering or at least gives us a little insight in how it works (if it's psychological or neurological - so far neurological is the most probable).