Who am I? 8

I have been headstrong and reckless

since I was a child.

One day when I displayed to

my classmates my new knife

I'd just bought,

one of them sarcastically said,

“If the knife is as good as you are proud,

why don’t you cut off your finger?”

When I heard this,

I flew into a rage

and tried to cut off my finger.

If some of my other friends had not stopped me,

I would have lost a finger that day.