I don't think it's only Samsung though. Apple fans are nervous because they're not used to being number 2 or number 3. I've followed Apple for years (look at my post count!) and I'm no rabid fanboy, but I prefer WP8 to Android, and the iPhone is somewhere in between.
Ehh I think people put too much into the whole "rankings".
Too be quite honest, Apple hasn't really EVER been number 1 as far as smartphone marketshare even in the US until only recently.
Before Q4 2012, Samsung had been number 1 since 2008......
People need to both justify their purchases and feel superior to others. Hence technology (which is becoming extremely personal as we all use and interact with our devices on a daily and sometimes hourly basis) has become one of those arenas where there are sides taken and people feel passionately (and often times illogically) about a certain product.
The marketing of each company also perpetuates this.
Many folks are inherently competitive. Anything they can latch onto to drive that nature with be latched on to. I should know, I'm immensely competitive myself. Its only been recently that I've begun to broaden my technological horizons.
Now I only get miffed when people make utterly ridiculous and asinine comments like "the iPhone is a worthless stale toy" or "Android is so buggy I can't do anything on it".
I still have trouble tolerating idiots