I'll join in.
As most, I started with 35mm, and while I do (did) enjoy it, and as much as there are amazing images being made with the small formats, whenever in image really hit me as outstanding, 99x out of 100, it was shot in MF or LF. Something about what is produced by the larger format just has a look that IMO can't be matched. Honestly, I can't really say what it is, but in my mind I can see the difference.
I also went back to film earlier this year, and develop my own B&W. This added something to the enjoyment of the hobby for me that was missing with digital.
Since I had this new found enjoyment, I decided I would get myself a 120 camera. First I went inexpensive, with a Franka Rollfix 6x9, but found the overall quality was lacking (no surprise). I then picked up an Ikoflex 6x6 (1934), and even with a less-then-perfect lens, I was finding that 'look' I wanted, and was prepared to make it my MF camera.
Then I got a phone call. My local lab knows I buy/sell camera stuff to support my hobby, and they referred a lady to me that had (in there words) 'a Minolta, I think, that is like new'. When I got the phone call, the lady corrected them, and said it was a Mamiya RB67 Pro-S with 'a bunch of extras'. Hmm.
So I meet the lady, and what she had was an RB67 Pro-SD, 90mm, 180mm, 3 WLF's, Prism Finder 2, 120 back, Mamiya/Polaroid Back (never used), hoods, caps, paperwork/manuals/catalogues, gadget bagk and hard case, and a few other odds and ends. The entire kit was bought new in '93 by her daughter, who unfortunately broke her wrist 2 months after buying the equipment ($6300), and it was put in a closet for 20+ years, and nothing has even the slightest indication of use.
We agreed on a price that in all honesty was too low, but that's because I based it on a Pro-S like she said, (I didn't even realize it was a Pro-SD until the next day), and it was the price she was asking.
I also picked up a Yashicamat 124G as my 6x6, as I decided I needed to sell the Ikoflex to fund the Mamiya, but still wanted the 6x6 format available. The Ikoflex has collector value as well as 'equipment' value, so it will pay for the Mamiya.
So that's kind of the how I got into MF. The why is because of the quality it produces versus the smaller formats.
Will I move into MF digital? Not anytime in the near future. The cost is completely unjustifiable to me as a hobbyist, but I would love to.
Since getting the RB67, I've added another 120 back, a 220 back, a 250mm, and a Kenko 2x TC for it, swivel grip, and Op-Tech neckstrap. I've committed myself to MF film, and to my local Insane Asylum. But I'm lovin' it!