I have one camera in every format I shoot: 35mm, 120, and 4x5.
I don't believe in buying cameras you don't need to make your art/tell your stories/run your business. One backup is OK, 2+ only if you're being paid to shoot and failure is not an option. You can "need" any model of camera you want, you don't have to buy a Yashica Electro instead of a Leica -- definitely pick the one that's right for you.
But collecting working cameras or buying them for aesthetics, etc., drives up prices (for all cameras, not just the collectors' items) for people who want to use them, takes them away from those film photography classes still available, and generally raises barriers to entry for film photography when we should be encouraging new blood to try it. Do you really need a Hasselblad 501cm, 503cx, and 201F? They are 90% the same. Why should you have a Minolta CLE, an M3 in several variations, and an M6? You also probably don't need a rangefinder and an SLR in the same format. If you want to try something new out, try it! But then pick one to get rid of after you've done so. These things aren't jewelry, they are tools for making art, telling stories, and running a photography business.
And no, it's not romantic or "paying your dues" for someone to get stuck with a Holga or Lubitel; It's just discouraging people. I met an artist and photographer the other day who wanted to try medium format, but couldn't afford anything in decent shape on the bay and worked too much to rummage through estate sales. You might say "try a cheap folder," but not everyone can handle those ancient, meterless cameras with patchy bellows, dark viewfinders, and uncoupled rangefinders. He just shrugged his shoulders. I tried to give him names of some less sought-after models... I hope he finds one.
Don't just accumulate cameras. Lend out your collection to artists and students long-term. Put them in the hands of people who will use them. If you do, our niche will grow in talent and vibrance, demand for film will increase (hello Ektachrome!), and maybe -- just maybe -- companies will find it worthwhile to manufacture new film cameras.