keyboard bravado

Engaging confident or brave talk or behavior that is intended to impress other people from the safety of being behind a keyboard instead of in person, usually accompanied by blustering swaggering conduct and a pretense of bravery. Can also describe the quality or state of being foolhardy on social media in a way that one wouldn't otherwise act in other circumstances.

What would have been an otherwise civil debate escalated into an online meltdown due to much keyboard bravado and fragile egos.