Wrongheaded (adjective)

Having or showing a mistaken or misguided opinion or approach.

Origin:

Wrong + headed.

Examples:

1. The decision was wrongheaded and ultimately led to the failure of the project.
2. He was wrongheaded in his belief that the company would be profitable.
3. He was wrongheaded in his approach, he ignored all the warnings and advice.
4. Her wrongheaded policies led to the downfall of the company.
5. His wrongheaded thinking led to poor decision making.