reckless

"foolhardy enough to try to seize the gun from the hijacker"; "became the fiercest and most reckless of partisans"-Macaulay; "a reckless driver"; "a rash attempt to climb Mount Everest"

"the heedless generosity and the spasmodic extravagance of persons used to large fortunes"- Edith Wharton; "reckless squandering of public funds"