I have a bike as a tool, rather than cycling as a hobby.
It's an incredibly flexible tool - bending to a whole range of tasks from doing the weekly shopping, commuting, family days out though to touring and even occasional sports (if you count audax as a sport). For me, one bike is enough. And, yes, it's a tourer.
I once dabbled with the lotsa-bikes way of life but just found I had lots of unused bikes. You can only ride one at a time and I'd just go through phases with each. And that's the nice thing about being bike monogamous - you can bond.