I have shot a life time of film already. I am looking for more. If you are not going to use yours then send all your film my way. BTW, 4x5 and larger are the formats I use.
"He who expecteth nothing,
Shall not be disappointed." Robert Willingham, 1907
Depends how long you expect to live, I'd guess.
At my peak consumption rate from the last three years, I'd go through about 100 rolls of 120 in a year, on average, about half that much 35 mm, and a couple hundred sheets of 9x12 cm or 4x5, but that rate was already constrained by budget when my budget was much healthier than it is now. If I could devote full time to photography, I'd probably at least triple those numbers -- and my wife might completely forget that we have two bathrooms, and call the police to report an intruder if we happened to meet in the hall.
Now, my family tends to be long-lived, though I'm a bit less healthy than some of them; I might reasonably expect to remain healthy enough to lug cameras around for another 40 years or so.
That suggests that (if I could reasonably expect it to keep that long), around 12,000 rolls of 120 B&W, 275 100 foot bulk rolls of 35 mm B&W and a couple hundred cassettes, and around 200 boxes of sheet film would probably last me the rest of my life. Heck, that'd all fit in a single "3 body Mafia freezer" unit.
I'll be able to get coffee forever, and I can make washing soda from baking soda if necessary, or use lye for alkali -- come to it, I could make up one of the old inorganic developers based on ferrous sulfate, acetic acid, and grain alcohol, so I'll be able to develop. Swimming pools don't look likely to go away, so I'll be able to find hypo, even if I have to buy it by the hundredweight (and there are other fixers -- potassium cyanide may be hazardous, but it fixes film, and fast). And I can dilute vinegar for stop bath (no, not with a cyanide fixer).
Photography has always fascinated me -- as a child, simply for the magic of capturing an image onto glossy paper with a little box, but as an adult because of the unique juxtaposition of science and art -- the physics of optics, the mechanics of the camera, the chemistry of film and developer, alongside the art in seeing, composing, exposing, processing and printing.
I think the term "lifetime" would probably pertain more to the life of the product and not the user. Even if you bought 50,000 rolls of your favorite film and the same amount of paper who knows if the film and paper would even produce acceptable results decades down the road. I guess I could use 30 year old film if I had to, but I doubt if the image quality would be that great. You could always store it in lead lined bags in the deep freeze but I doubt many people would go to such great expense of money and space. Thats why I haven't stock piled large numbers of Tech-pan, Polymax or APX 100 in 120. I find it depressing to prolong the misery of knowing that one day these things will be no more and each exposure is a count down to the end! I'd rather be done with it quick and find a replacement and once all the replacements are gone then I'll find another hobby.