Softheadedness is when someone is not very smart or makes silly decisions.
Softheadedness is not a good thing because it means someone is not very clever.
Examples:
His softheadedness led him to believe the fake news.
She showed her softheadedness by trying to use a broken umbrella in the rain.
The softheadedness of the plan was obvious to everyone.
The softheadedness of the cat trying to catch its own tail made everyone laugh.
The softheadedness of thinking you can fly like a bird is very dangerous.
His softheadedness is like a big, dark cloud over his head.