Foolhardiness
/ˈfuːlhɑːrdinəs/
Definition 1 of 1
Pro Tip 1/3Negative Connotation
Foolhardiness usually implies criticism for lack of judgment, rather than bravery. 
Many viewed his investment in the failing company as foolhardiness.
Pro Tip 2/3Often Unplanned
Foolhardiness typically suggests acting without proper thought or plan. 
His foolhardiness caused him to jump into the river without checking the depth.
Pro Tip 3/3Potentially Dangerous
The term often implies that the action could lead to harm or danger. 
The hikers showed foolhardiness by ignoring the storm warnings.