i can swim to save myself, but even so, when I'm embark on such small vessel and especially with friends, it is better to be wearing safety floatation than to second wish you had on a safety vest. Under sudden distress, the mind can panic and things could happen beyond your control. The water, the weather, the adrenaline rush, all can factor in you drowning.
These young kids obviously, think not with their heads, but their cockiness got the best of them. My condolences, nonetheless.