Doxxing is the practice of searching for and publishing private, identifiable information about a person or persons on the internet, usually with malicious intent. In the crypto space, a doxxed individual is one who shares personal information about themselves in the public domain online that could put them at risk.
Slang for "dropping documents," doxxing is considered a form of cyberbullying if done by a malicious user. Several cryptocurrency investors prefer to remain anonymous online, using avatars and pseudonyms, e.g., Satoshi Nakamoto - the creator of Bitcoin. This protects them from scams and possible hack attacks.
However, doxxing is a good practice for developers and creators behind crypto projects. Revealing their identities makes their projects seem more credible, encouraging investors to trust them and back their projects.