Usually you start becoming data hoarder when something that you expected to be online and what you can freely access (e.g. bought video games/series on PSStore/Netflix) becomes inaccessable due to various reasons:
- Platform policies - if content/account violates guidelines [it gets removed](https://www.reddit.com/r/OneFinanceBank/comments/1d8cixt/did_they_just_take_down_the_other_one_subreddit/) (e.g. for hate speech, misinformation, or copyright infringement...)
- Legal reason - content may be removed due to legal issues, such as [DMCA takedown](https://www.dmca.com/FAQ/What-is-a-DMCA-Takedown), [court orders](https://www.newsbytesapp.com/news/entertainment/bombay-high-court-protects-arijit-singhs-personality-rights/story), [political stuff](https://www.reuters.com/business/media-telecom/youtube-blocks-russian-state-funded-media-channels-globally-2022-03-11/)
- Technical issues - drive on server may die and sysadmin forgot to try make disaster recovery beforehand, [cloud sync errors](https://spanning.com/blog/4-real-life-examples-of-saas-data-loss/)
- Archiving - platform may decide that this content no longer relevant/needed - so they move it to more harder to access place