Oh my! I guess I'm in the minority here, haha. I have one embroidery-only machine, one serger, and two sewing machines- my Janome 6600 and then a 1930s era Singer 15-88 that I have for upholstery, leather, and other heavy-duty projects that I don't want to subject my Janome to.
I may get one more machine in the future solely for quilting (either a long-arm or a medium-arm that I can use on a quilting frame) but I can't imagine having more machines! I mean- with the exception of the embroidery machine, which I can set up and then let it do its thing, I can only use one machine at a time, so I personally think it's a waste for me to have a lot of machines that will just sit there most of the time.
But I will admit that I'm not a collector :) And even if I was, I don't have the space!