long-term archival is hard and you will probably need to move your shit to other media over time
you will also want checksums and redundant copies on the media - if you do end up in the unfortunate case of dealing with actual bit-rot, it likely won't affect every single file

one big thing too is for shit you've downloaded - you want a big list of filenames, original post IDs, etc (and this is very easy to back up to way more places than your main data pile), so if you did end up losing them, you can maybe attempt to get from another source (maybe even the original source if you're lucky)

even ordinary optical media can last decades while reading fine (in particular, I have burned games from like 18 years ago that verify 1:1, at least for anything where I still had the original files to verify against)
but cheap media like what I burned isn't really rated for more than like 10 years, so I could have issues at any time and I'd have to suck that up

it's all just kinda difficult for your collection of media to definitively last over a normal human lifetime
and if you want some information to be preserved for the ages, etch it into stainless steel or something and bury it lmao