He was elected as president of a constitutional republic. He's acting like an emperor, enacting control through cronyism, threats and targeting of individuals and private companies via executive power. You could counter that he was elected by people who wanted to disrupt the system but that's a massive assumption and even many of his political base seem to be surprised by the extent of his actions. There is constantly political alignment behind his actions, with aligned politicians & media noticeably readjusting their opinions, politics and bills and revising history to align with the latest demagoguery to appear from this one person.

The constitutional republic was designed to protect from one person's whims but that ideal seems to have crumbled when the rest of the republic has been co-opted, controlled or simply ignored. In Europe we always knew that US claims to have the best democratic system were hubristic nonsense, no maybe more in the US realise the fragility of government.

An elected person can both have and act upon whims, including ones their supporters might not approve of.