Regime change was never assured and no one ever assumed it would clearly happen. It was never a defining requirement of pending US military action.
Iran has suffered billions and billions in destruction and damages from the war. Their air force is gone. Their navy is gone. Their nuclear program is set back 25 years for sure and possibly gone altogether. Their entire political leadership from the supreme leader down are dead. Their nuclear scientists are dead. The rest of their military and missiles are crushed and set back more than a decade.
The military action achieved all its required goals.
And the US isn’t responsible to achieve Israel’s goals. Additionally, President Trump has helped Israel in the past almost 18 months more than any other presidential candidate would have in eight years.