Alarmism

Alarmism is excessive or exaggerated alarm about a real or imagined threat. In the news media, alarmism can be a form of yellow journalism where reports sensationalise a story to exaggerate small risks.
Alarmist personality.
The alarmist person is subject to the cognitive distortion of catastrophizing – of always expecting the worst of possible futures.
They may also be seeking to preserve feelings of omnipotence by generating anxiety and concern in others.
False accusation.
The charge of alarmism can of course be used to discredit a legitimate warning, as when Churchill was widely dismissed as an alarmist in the 1930s.