Rare Twitter/Instagram handles in tech/otherwise?

At Twitter, the 3 character and less names are deprecated - aiui they won't reclaim unused ones for anyone. If you've got one, it's kindof a status symbol as an early user but also a pita as people are always going through those and trying to guess passwords due to their desirability. As far as the rest, they removed the policy that allowed employees to claim inactive usernames many years back. These days you generally need to be a) a more than trivial brand and b) the handle has to contain one if your trademarks. Handles are only eligible for this if they're inactive which is something like over 6 months of no logins AND a mostly unused account for it's lifetime (there are some pretty low thresholds in number of tweets or retweets per year iirc) Brands and others can and do purchase handles from individuals though. This happens without any interaction on the part of the platform (just a direct password handover).