I started with my first dSLR (7D) to replace my digital P&S a few years ago (although I had fond memories of my mum letting me even touch her spotmatic when I was a kid). Boredom at work led me to discover the ability to mount Pentacon Six lenses to my eos with a tilt/shift adapter. Then I started researching the rest of the P6-family, then buying (GAS attack to the max).
The final straw for me was when the 5D mk3 got released, a camera I was sure I'd buy on-release as an upgrade to my 7D. Then I saw the price, and the fact that they'd prioritised high-iso over more-MP and low-iso performance didn't help.
Then I discovered Velvia, and after much researching I reckoned I could scan/print Velvia to about the same size as a 5D3 (at least for landscapes, give or take a bit depending on quality). Did some calculations, and for the price of a 5D3 I bought an EOS 3 with $3000 left to put towards film over the years (2 years later, I'm probably a few hundred dollars through that, including my very-full freezer).
Then, seeing as I already had the P6 lenses, I bought into some cameras too (more GAS). I thought at the time, if I can get 5D3-quality out of 35mm velvia, I should easily get better with MF, which I can scan to higher-res, and still at a fraction of the (initial) cost.

So initially it was all about the quality, and especially the quality/price ratio, that neverending quest for more-MP (scanned or digital). But I realised a while ago, and it hammered home again today, that I don't actually print billboards. I've got a 13" printer but haven't done much above A4 (yet, I will one day).

Today it hammered-home because I've bought a 480mm enlarger lens with no shutter, and I'm going to have to a) hack it onto a shutter, probably a packard; b) hack said shutter onto my Tovoview somehow; c) extend the bellows and tubes far enough to get it to focus; d) mount it somehow that it doesn't just tip my whole tripod over in the wind; e) work out some flash/lighting rig with short enough duration to deal with a potentially slow shutter; f) convince someone to sit in front of it for a few minutes while I focus the damn thing and calculate exposures and all that.
And there's where I get my fun (if you can't tell, I'm an engineer for a reason), the thing gathering light at the other end doesn't matter, it's just that film is a buttload cheaper than a 4x5 digital sensor (which only exist as scanning backs afaik, and definitely not in my price range). And if I get a good photo out of it that's a bonus.