I can’t tell if you are saying only ripping content helps preserve it or that seeding does too. I download things but seed them as long as possible. (Technically until I run out of disk space, but that hasn’t happened yet and I think I will upgrade before it does.) Considering how many pirates download things and keep seeding, I think the pirates that don’t help preserve stuff could be the minority.
I don’t have the originals, but I am happy to say I have all of the 1963 and 2005 Doctor Whos (with the exception of some new stuff… I should really get sonarr.) They are on i2p and I am still seeding if anyone wants them.