Good advice in general, but for anything older than this year, there's a big torrent floating out there. I suspect you'd be able to find your content no problem even if reddit goes belly up.
Not knocking this method, just letting folks know that if you do miss the window to do this, there might still be a fallback option for you. See https://kbin.social/m/RedditMigration/t/65260/PSA-Here-s-exactly-what-to-do-if-you-hit-the