You can disagree with his politics (if you like), you can make an argument regarding exactly what he has achieved or not achieved, but to suggest that he has 'limited intelligence' reeks of either envy or polarised politics. And even if he has 'failed at everything', he has hardly 'ruined' anything.

Humanity's Greatest Inventions:

No. 1. Indoor plumbing (flush toilet/sewerage system)

Between this and hand washing, the greatest single medical intervention ever. Prevents cholera etc. Antibiotics came much later.

No. 2. Washing machine (for clothes)

Greatest labour saving device ever, for an absolutely necessary ongoing household task.